SGV TOAN 4

["GV y\u00eau c\u1ea7u HS gi\u1ea3i th\u00edch m\u1ed9t v\u00e0i tr\u01b0\u1eddng h\u1ee3p, kh\u00f4ng nh\u1ea5t thi\u1ebft gi\u1ea3i th\u00edch t\u1ea5t c\u1ea3 c\u00e1c c\u00e2u. Ch\u1eb3ng h\u1ea1n, c\u00f3 th\u1ec3 h\u1ecfi theo c\u00e1c c\u00e1ch d\u01b0\u1edbi \u0111\u00e2y: \u2026\u2022\u2022\u2022\u2022 PTTP\u1ea1\u1ea1hhii\u00e2\u00e2ssnnaaooss\u1ed1\u1ed1el\u1ea1m4433i lcc\u00e0vhhip\u1ec9\u1ec9\u1ebfhtp\u0111h\u00e2ip\u1ec1nh\u1ea7un\u00e2sgn\u1ed1\u0111\u00ec?\u00e3s34\u1ed1(tmh\u00f4na\u00e0hmy\u01b0k\u00e0bhuvi\u1ec3\u00f4\u1eadcuny\u1ee7?gtahl\u1ecbh\u00e0\u0111\u00ec34ni\u2009\u1ec1h?ung\u00e0\u00eco?)? (Ch\u1ec9 ph\u1ea7n \u0111\u00e3 t\u00f4 m\u00e0u trong H\u00ecnh 2.) 2. Luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m. \u2013 HS \u0111\u1ecdc y\u00eau c\u1ea7u, nh\u1eadn bi\u1ebft c\u00e1c vi\u1ec7c c\u1ea7n l\u00e0m (t\u01b0\u01a1ng t\u1ef1 Th\u1ef1c h\u00e0nh 1) r\u1ed3i th\u1ef1c hi\u1ec7n theo m\u1eabu. 3 H\u00ecnh B: 261\t\t 12 H\u00ecnh A: 21 H\u00ecnh C: 21 B\u00e0i 2: \u2013 HS th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. \u2013 HS \u0111\u1ecdc y\u00eau c\u1ea7u, nh\u1eadn bi\u1ebft c\u00e1c vi\u1ec7c c\u1ea7n l\u00e0m. HS vi\u1ebft ng\u1eafn g\u1ecdn: 132\t 1 Rau c\u1ea3i: 162\t\t 2 Hoa h\u1ed3ng: Hoa c\u00fac: 12 \t \t C\u00e0 chua: 12 \u2013 S\u1eeda b\u00e0i: 1 HS n\u00f3i c\u1ea3 c\u00e2u, ch\u1eb3ng h\u1ea1n: Hoa c\u00fac \u0111\u01b0\u1ee3c tr\u1ed3ng tr\u00ean 12 m\u1ea3nh \u0111\u1ea5t. HS gi\u1ea3i th\u00edch m\u1ed9t v\u00e0i tr\u01b0\u1eddng h\u1ee3p, ch\u1eb3ng h\u1ea1n: M\u1ea3nh \u0111\u1ea5t \u0111\u01b0\u1ee3c chia th\u00e0nh 12 ph\u1ea7n b\u1eb1ng nhau, c\u00f3 1112p.h\u1ea7n t\u00f4 m\u00e0u v\u00e0ng \u0111\u1ec3 tr\u1ed3ng hoa c\u00fac n\u00ean ph\u00e2n s\u1ed1 ch\u1ec9 ph\u1ea7n tr\u1ed3ng hoa c\u00fac tr\u00ean m\u1ea3nh \u0111\u1ea5t l\u00e0 IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 3: a) \u0110 b) \u0110 c) S (12 l\u00e0 t\u1eed s\u1ed1 c\u1ee7a ph\u00e2n s\u1ed1 172) d) \u0110 Vui h\u1ecdc Th\u1ef1c hi\u1ec7n nh\u00f3m b\u1ed1n. \u2013 HS \u0111\u1ebfm: T\u1ea5t c\u1ea3 s\u1ed1 con v\u1eadt trong b\u1ee9c tranh. S\u1ed1 con v\u1eadt m\u1ed7i lo\u1ea1i \u0111\u1ec3 vi\u1ebft ph\u00e2n s\u1ed1 (136\u2009, 146\u2009, 176). \u2013 S\u1eeda b\u00e0i, khuy\u1ebfn kh\u00edch HS n\u00f3i c\u1ea3 c\u00e2u theo m\u1eabu. L\u01b0u \u00fd: Trong t\u00ecnh hu\u1ed1ng n\u00e0y, 16 ph\u1ea7n b\u1eb1ng nhau kh\u00f4ng l\u00e0 16 con v\u1eadt b\u1eb1ng nhau v\u1ec1 h\u00ecnh d\u1ea1ng. S\u1ef1 b\u1eb1ng nhau th\u1ec3 hi\u1ec7n v\u1ec1 m\u1eb7t s\u1ed1 l\u01b0\u1ee3ng: c\u00e1c con v\u1eadt kh\u00e1c nhau nh\u01b0ng m\u1ed7i con \u0111\u1ec1u th\u1ec3 hi\u1ec7n l\u00e0 1 con (d\u00f9 l\u1edbn hay b\u00e9). 250","B\u00e0i 61. PH\u00c2N S\u1ed0 V\u00c0 PH\u00c9P CHIA S\u1ed0 T\u1ef0 NHI\u00caN (2 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS nh\u1eadn bi\u1ebft v\u00e0 th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c vi\u1ec7c vi\u1ebft th\u01b0\u01a1ng c\u1ee7a ph\u00e9p chia s\u1ed1 t\u1ef1 nhi\u00ean cho s\u1ed1 t\u1ef1 nhi\u00ean (kh\u00e1c 0) d\u01b0\u1edbi d\u1ea1ng ph\u00e2n s\u1ed1 v\u00e0 ng\u01b0\u1ee3c l\u1ea1i. \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn ph\u00e2n s\u1ed1, bi\u1ec3u \u0111\u1ed3 c\u1ed9t. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc; giao ti\u1ebfp to\u00e1n h\u1ecdc; m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c; s\u1eed d\u1ee5ng c\u00f4ng c\u1ee5, ph\u01b0\u01a1ng ti\u1ec7n h\u1ecdc to\u00e1n; gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t nh\u00e2n \u00e1i, tr\u00e1ch nhi\u1ec7m. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh c\u00f3 trong b\u00e0i (n\u1ebfu c\u1ea7n). HS: Gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng. C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ch\u01a1i tr\u00f2 ch\u01a1i \u201cT\u00f4i b\u1ea3o\u201d. \u2013 GV: T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? \u2013 GV: T\u00f4i b\u1ea3o c\u00e1c b\u1ea1n vi\u1ebft ph\u00e9p t\u00ednh c\u1ee7a b\u00e0i to\u00e1n: Chia \u0111\u1ec1u 4 c\u00e1i b\u00e1nh cho 4 b\u1ea1n, m\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c m\u1ea5y c\u00e1i b\u00e1nh? \u2013 HS: 4 : 4 = 1. \u2013 GV : T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? \u2013 GV: T\u00f4i b\u1ea3o c\u00e1c b\u1ea1n vi\u1ebft ph\u00e9p t\u00ednh c\u1ee7a b\u00e0i to\u00e1n: Chia \u0111\u1ec1u 20 c\u00e1i b\u00e1nh cho 4 b\u1ea1n, m\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c m\u1ea5y c\u00e1i b\u00e1nh? \u2013 HS: 20 : 4 = 5 \u2013 GV: T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? \u2013 GV: T\u00f4i b\u1ea3o c\u00e1c b\u1ea1n vi\u1ebft ph\u00e9p t\u00ednh c\u1ee7a b\u00e0i to\u00e1n: Chia \u0111\u1ec1u 3 c\u00e1i b\u00e1nh cho 4 b\u1ea1n, m\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c m\u1ea5y c\u00e1i b\u00e1nh? \u2013 HS: 3 : 4 = !!! \u2013 GV: Ch\u00fang ta t\u00ecm k\u1ebft qu\u1ea3 c\u1ee7a ph\u00e9p chia. GV vi\u1ebft b\u1ea3ng: 3 : 4 = ? II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: Ph\u00e2n s\u1ed1 v\u00e0 ph\u00e9p chia s\u1ed1 t\u1ef1 nhi\u00ean 1. V\u00ed d\u1ee5 1 \u2013 HS gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1. \u2022 B\u01b0\u1edbc 1: T\u00ecm hi\u1ec3u v\u1ea5n \u0111\u1ec1 Nh\u1eadn bi\u1ebft v\u1ea5n \u0111\u1ec1 c\u1ea7n gi\u1ea3i quy\u1ebft: T\u00ecm k\u1ebft qu\u1ea3 c\u1ee7a ph\u00e9p chia 3 : 4 = ? T\u1ee9c l\u00e0 t\u00ecm xem m\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c bao nhi\u00eau c\u00e1i b\u00e1nh. 251","\u2022 B\u01b0\u1edbc 2: L\u1eadp k\u1ebf ho\u1ea1ch N\u00eau \u0111\u01b0\u1ee3c c\u00e1ch th\u1ee9c GQV\u0110 (c\u00f3 th\u1ec3 d\u00f9ng gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng, \u0110DHT, \u2026). \u2022 B\u01b0\u1edbc 3: Ti\u1ebfn h\u00e0nh k\u1ebf ho\u1ea1ch HS th\u1ef1c h\u00e0nh chia b\u00e1nh tr\u00ean m\u00f4 h\u00ecnh h\u00ecnh v\u1ebd. Tr\u00ecnh b\u00e0y tr\u01b0\u1edbc l\u1edbp. \u2022 B\u01b0\u1edbc 4: Ki\u1ec3m tra l\u1ea1i C\u00e1c ph\u1ea7n c\u1ee7a 4 b\u1ea1n c\u00f3 b\u1eb1ng nhau? G\u1ed9p c\u1ea3 4 ph\u1ea7n c\u00f3 b\u1eb1ng 3 c\u00e1i b\u00e1nh? \u2013 GV h\u1ec7 th\u1ed1ng l\u1ea1i vi\u1ec7c l\u00e0m c\u1ee7a c\u00e1c nh\u00f3m. \u2022 M\u00f4 h\u00ecnh 3 c\u00e1i b\u00e1nh tr\u00ean gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng. \u2022 Do c\u00f3 4 b\u1ea1n n\u00ean m\u1ed7i c\u00e1i b\u00e1nh chia th\u00e0nh 4 ph\u1ea7n b\u1eb1ng nhau. \u2022 Chia tr\u00ean h\u00ecnh v\u1ebd. An H\u00e0 An H\u00e0 An H\u00e0 L\u00ea T\u00fa L\u00ea T\u00fa L\u00ea T\u00fa \u2022 M\u1ed7i c\u00e1i b\u00e1nh chia th\u00e0nh 4 ph\u1ea7n b\u1eb1ng nhau, m\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c 3 ph\u1ea7n nh\u01b0 th\u1ebf, t\u1ee9c l\u00e0 m\u1ed7i 3 b\u1ea1n \u0111\u01b0\u1ee3c 4 c\u00e1i b\u00e1nh. \u2013 GV k\u1ebft lu\u1eadn. \t\t 3 : 4 = 3 4 Th\u01b0\u01a1ng c\u1ee7a ph\u00e9p chia 3 : 4 c\u00f3 th\u1ec3 vi\u1ebft th\u00e0nh m\u1ed9t ph\u00e2n s\u1ed1, t\u1eed s\u1ed1 l\u00e0 s\u1ed1 b\u1ecb chia 3 v\u00e0 m\u1eabu s\u1ed1 l\u00e0 s\u1ed1 chia 4. 252","2. V\u00ed d\u1ee5 2 HS (nh\u00f3m b\u1ed1n) th\u1ef1c hi\u1ec7n theo c\u00e1c b\u01b0\u1edbc t\u01b0\u01a1ng t\u1ef1 nh\u01b0 V\u00ed d\u1ee5 1 \u2192 K\u1ebft lu\u1eadn. \t\t 5 : 4 = 5 4 Th\u01b0\u01a1ng c\u1ee7a ph\u00e9p chia 5 : 4 c\u00f3 th\u1ec3 vi\u1ebft th\u00e0nh m\u1ed9t ph\u00e2n s\u1ed1, t\u1eed s\u1ed1 l\u00e0 s\u1ed1 b\u1ecb chia 5 v\u00e0 m\u1eabu s\u1ed1 l\u00e0 s\u1ed1 chia 4. 3. Kh\u00e1i qu\u00e1t \u2013 GV v\u1eeba v\u1ea5n \u0111\u00e1p, v\u1eeba vi\u1ebft l\u00ean b\u1ea3ng l\u1edbp. \t\t 3 : 4 = 3 \u2192 S\u1ed1 b\u1ecb chia \t\t 5 : 4 = 5 \u2192 S\u1ed1 b\u1ecb chia 4 S\u1ed1 chia 4 S\u1ed1 chia T\ufeffh\u01b0\u01a1ng c\u1ee7a ph\u00e9p chia s\u1ed1 t\u1ef1 nhi\u00ean cho s\u1ed1 t\u1ef1 nhi\u00ean (kh\u00e1c 0) c\u00f3 th\u1ec3 vi\u1ebft th\u00e0nh m\u1ed9t ph\u00e2n s\u1ed1, t\u1eed s\u1ed1 l\u00e0 s\u1ed1 b\u1ecb chia v\u00e0 m\u1eabu s\u1ed1 l\u00e0 s\u1ed1 chia. III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 GV c\u00f3 th\u1ec3 g\u1ee3i \u00fd HS th\u1ef1c hi\u1ec7n theo m\u1ed9t tr\u00ecnh t\u1ef1 \u0111\u1ec3 HS d\u1ec5 d\u00e0ng tr\u00ecnh b\u00e0y khi s\u1eeda b\u00e0i. V\u00ed d\u1ee5: Chia \u0111\u1ec1u \u2026 c\u00e1i b\u00e1nh cho \u2026 b\u1ea1n \u2192 Chia c\u00e1i b\u00e1nh th\u00e0nh \u2026 ph\u1ea7n b\u1eb1ng nhau \u2192 M\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c \u2026 ph\u1ea7n \u2192\u2026:\u2026= \u2026 \u2026 \u2013 HS th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, khuy\u1ebfn kh\u00edch c\u00e1c em tr\u00ecnh b\u00e0y. a) Chia \u0111\u1ec1u 1 c\u00e1i b\u00e1nh cho 4 b\u1ea1n \u2192 Chia c\u00e1i b\u00e1nh th\u00e0nh 4 ph\u1ea7n b\u1eb1ng nhau \u2192 M\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c 1 ph\u1ea7n 1 \u2192 1 : 4 = 4 . b) Chia \u0111\u1ec1u 1 c\u00e1i b\u00e1nh cho 3 b\u1ea1n \u2192 Chia c\u00e1i b\u00e1nh th\u00e0nh 3 ph\u1ea7n b\u1eb1ng nhau \u2192 M\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c 1 ph\u1ea7n 1 \u2192 1 : 3 = 3 . c) Chia \u0111\u1ec1u 2 c\u00e1i b\u00e1nh cho 5 b\u1ea1n \u2192 Chia m\u1ed7i c\u00e1i b\u00e1nh th\u00e0nh 5 ph\u1ea7n b\u1eb1ng nhau \u2192 M\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c 2 ph\u1ea7n 2 \u2192 2:5= 5 . 253","d) Chia \u0111\u1ec1u 3 c\u00e1i b\u00e1nh cho 2 b\u1ea1n \u2192 Chia m\u1ed7i c\u00e1i b\u00e1nh th\u00e0nh 2 ph\u1ea7n b\u1eb1ng nhau \u2192 M\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c 3 ph\u1ea7n 3 \u2192 3 : 2 = 2 . B\u00e0i 2: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n. 3 9 6 14 10 8 6 14 : 7 = 7 \t 3 : 10 = \t\t 9:8= \t 6:6= B\u00e0i 3: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n. 18 = 18 : 6 \t 50 = 50 : 10 \t 15 = 15 : 15 12 = 12 : 24 6 10 15 24 L\u01b0u \u00fd: \u0110\u1ed1i v\u1edbi B\u00e0i 2 v\u00e0 B\u00e0i 3, GV c\u00f3 th\u1ec3 v\u1eadn d\u1ee5ng ph\u01b0\u01a1ng ph\u00e1p nh\u00f3m c\u00e1c m\u1ea3nh gh\u00e9p t\u1ed5 ch\u1ee9c cho HS th\u1ef1c hi\u1ec7n \u0111\u1ed3ng th\u1eddi c\u1ea3 hai b\u00e0i. 2. Luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n (theo m\u1eabu). 8 7 18 45 8 1 3 = 18 : 3 = 6\t 9 = 45 : 9 = 5\t = 8 : 8 = 1\t\t = 7 : 1 = 7 \t B\u00e0i 2: 6 1 \u2013 T\u00ecm hi\u1ec3u m\u1eabu: T\u1ea1i sao 6 = ? (V\u00ec 6 : 1 = 6.) \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n. IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 3: \u2013 HS th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, GV khuy\u1ebfn kh\u00edch HS gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. MCCC\u00e1\u00e1\u00e1\u1ed7iiiibbbc\u00e1\u00e1\u00e1\u00e1nnni hhhb\u00e1cccnhhhhiiiaaacttthhhhi\u00e0\u00e0\u00e0annnthhhh\u00e0885nppphhhh5\u1ea7\u1ea7\u1ea7nnnphbbb\u1ea7\u1eb1\u1eb1\u1eb1nnnngggb\u1eb1nnnnhhhgaaauuun,,,hllla\u1ea5\u1ea5\u1ea5uyyy,c5cl\u1ea3\u1ea3\u1ea5py85h8\u1ea7ppnphhh\u1ea7\u1ea7\u2192nn\u1ea7n\u2192\u219258\u219255c88\u00e185cic\u00e1\u00e1bcii\u00e1\u00e1bbni\u00e1\u00e1hbnn\u00e1\u2192hhnh\u2192\u2192C\u2192\u00e2CCu\u00e2C\u00e2Buu\u00e2.uCD.A. . H\u00ecnh 1: H\u00ecnh 2: H\u00ecnh 3: H\u00ecnh 4: B\u00e0i 4: a) \u0110 3 5 b) S (3 : 5 = ) c) \u0110 (M\u1eabu s\u1ed1 c\u1ee7a ph\u00e2n s\u1ed1 c\u00f3 vai tr\u00f2 l\u00e0 s\u1ed1 chia trong ph\u00e9p chia, s\u1ed1 chia lu\u00f4n kh\u00e1c 0.) d) \u0110 (Khi l\u1ea5y t\u1eed chia cho m\u1eabu \u0111\u1ec1u \u0111\u01b0\u1ee3c th\u01b0\u01a1ng l\u00e0 7.) 254","B\u00e0i 5: \u2013 T\u00ecm hi\u1ec3u m\u1eabu. \u0110o\u1ea1n th\u1eb3ng AB \u0111\u01b0\u1ee3c chia th\u00e0nh 3 ph\u1ea7n b\u1eb1ng nhau, \u0111o\u1ea1n th\u1eb3ng AM g\u1ed3m 2 ph\u1ea7n nh\u01b0 th\u1ebf. 2 2 AM = 3 AB \u2192 Ta n\u00f3i: \u0110\u1ed9 d\u00e0i \u0111o\u1ea1n th\u1eb3ng AM b\u1eb1ng 3 \u0111\u1ed9 d\u00e0i \u0111o\u1ea1n th\u1eb3ng AB. \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n r\u1ed3i chia s\u1ebb nh\u00f3m. \u2013 S\u1eeda b\u00e0i, GV khuy\u1ebfn kh\u00edch c\u00e1c em tr\u00ecnh b\u00e0y. \u2013 \u0110o\u1ea1n th\u1eb3ng CD \u0111\u01b0\u1ee3c chia th\u00e0nh 4 ph\u1ea7n b\u1eb1ng nhau, \u0111o\u1ea1n th\u1eb3ng CK g\u1ed3m 1 ph\u1ea7n, \u0111o\u1ea1n th\u1eb3ng KD g\u1ed3m 3 ph\u1ea7n nh\u01b0 th\u1ebf. CK = 1 CD; SV = 3 TV 4 4 Vui h\u1ecdc \u2013 HS nh\u1eadn bi\u1ebft qu\u00e3ng \u0111\u01b0\u1eddng t\u1eeb tr\u01b0\u1eddng v\u1ec1 nh\u00e0 \u0111\u01b0\u1ee3c chia th\u00e0nh 7 ph\u1ea7n b\u1eb1ng nhau, S\u00ean \u0111\u00e3 b\u00f2 \u0111\u01b0\u1ee3c 5 ph\u1ea7n. 5 \u2013 B\u1ea1n S\u00ean \u0111\u00e3 b\u00f2 \u0111\u01b0\u1ee3c 7 qu\u00e3ng \u0111\u01b0\u1eddng t\u1eeb tr\u01b0\u1eddng v\u1ec1 nh\u00e0. Th\u1eed th\u00e1ch \u2013 T\u00ecm hi\u1ec3u bi\u1ec3u \u0111\u1ed3. Bi\u1ec3u \u0111\u1ed3 cho bi\u1ebft g\u00ec? (L\u01b0\u1ee3ng n\u01b0\u1edbc u\u1ed1ng trong m\u1ed9t ng\u00e0y c\u1ee7a m\u1ed9t s\u1ed1 b\u1ea1n.) M\u1ea5y b\u1ea1n? (4 b\u1ea1n) \u0110\u1ecdc t\u00ean c\u00e1c b\u1ea1n (An, T\u00fa, L\u00ea, H\u00e0). Chi\u1ec1u cao m\u1ed7i c\u1ed9t m\u00e0u \u1edf bi\u1ec3u \u0111\u1ed3 bi\u1ec3u th\u1ecb \u0111i\u1ec1u g\u00ec? (L\u01b0\u1ee3ng n\u01b0\u1edbc u\u1ed1ng c\u1ee7a m\u1ed7i b\u1ea1n.) L\u01b0\u1ee3ng n\u01b0\u1edbc u\u1ed1ng t\u00ednh theo \u0111\u01a1n v\u1ecb n\u00e0o? (l\u00edt) \u0110\u1ecdc c\u00e1c s\u1ed1 \u1edf c\u1ed9t ngo\u00e0i c\u00f9ng b\u00ean tr\u00e1i (0 l, 1 l, 2 l). \u2013 Nh\u00f3m b\u1ed1n d\u1ef1a v\u00e0o bi\u1ec3u \u0111\u1ed3, nh\u1eadn bi\u1ebft l\u01b0\u1ee3ng n\u01b0\u1edbc m\u1ed7i b\u1ea1n u\u1ed1ng (theo \u0111\u01a1n v\u1ecb l\u00edt). \u2013 S\u1eeda b\u00e0i. C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c tr\u00f2 ch\u01a1i thi \u201cAi nhanh h\u01a1n\u201d. C\u00e1c nh\u00f3m gi\u1ea3i th\u00edch k\u1ebft qu\u1ea3. M\u1ed7i l\u00edt n\u01b0\u1edbc (c\u1ed9t s\u1ed1 b\u00ean tr\u00e1i) \u0111\u01b0\u1ee3c chia th\u00e0nh 5 ph\u1ea7n b\u1eb1ng nhau. An: 7 ph\u1ea7n \u2192 7 l n\u01b0\u1edbc. 5 8 T\u00fa: 8 ph\u1ea7n \u2192 5 l n\u01b0\u1edbc. L\u00ea: 6 ph\u1ea7n \u2192 6 l n\u01b0\u1edbc. 5 9 H\u00e0: 9 ph\u1ea7n \u2192 5 l n\u01b0\u1edbc. 255","B\u00e0i 62. PH\u00c2N S\u1ed0 B\u1eb0NG NHAU (2 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS nh\u1eadn bi\u1ebft t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1, t\u1eeb \u0111\u00f3 nh\u1eadn bi\u1ebft c\u00e1c ph\u00e2n s\u1ed1 b\u1eb1ng nhau; th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c vi\u1ec7c t\u00ecm c\u00e1c ph\u00e2n s\u1ed1 b\u1eb1ng nhau. \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn c\u00e1c ph\u00e2n s\u1ed1 b\u1eb1ng nhau. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc; giao ti\u1ebfp to\u00e1n h\u1ecdc; m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c; s\u1eed d\u1ee5ng c\u00f4ng c\u1ee5, ph\u01b0\u01a1ng ti\u1ec7n h\u1ecdc to\u00e1n; gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t nh\u00e2n \u00e1i, trung th\u1ef1c. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh c\u00f3 trong b\u00e0i (n\u1ebfu c\u1ea7n). HS: M\u1ed7i HS m\u1ed9t b\u0103ng gi\u1ea5y, k\u00edch th\u01b0\u1edbc m\u1ed7i b\u0103ng gi\u1ea5y 6 \u00f4 \u00d7 1 \u00f4 (c\u00e1c b\u0103ng gi\u1ea5y c\u1ee7a HS b\u1eb1ng nhau). C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ch\u01a1i tr\u00f2 ch\u01a1i \u201cT\u00f4i b\u1ea3o\u201d. \u2013 GV: T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? \u2013 GV: T\u00f4i b\u1ea3o c\u00e1c b\u1ea1n nam vi\u1ebft ph\u00e2n s\u1ed1 ch\u1ec9 s\u1ed1 b\u00e1nh c\u1ee7a b\u00e9 trai \u0103n, c\u00e1c b\u1ea1n n\u1eef vi\u1ebft ph\u00e2n s\u1ed1 ch\u1ec9 s\u1ed1 b\u00e1nh c\u1ee7a b\u00e9 g\u00e1i \u0103n. \u2013 HS l\u00e0m theo. 2 1 8 Nam: 4 \t N\u1eef: \u2013 GV: T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? \u2013 GV: T\u00f4i b\u1ea3o c\u00e1c b\u1ea1n so s\u00e1nh ph\u1ea7n b\u00e1nh hai b\u00e9 \u0103n. \u2013 HS: \u201cB\u1eb1ng nhau! \u2013 GV: T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? 1 2 4 8 \u2013 GV: T\u00f4i b\u1ea3o so s\u00e1nh hai ph\u00e2n s\u1ed1 v\u00e0 . \u2013 HS: \u201cHai ph\u00e2n s\u1ed1 b\u1eb1ng nhau! \u2013 GV: Hai ph\u00e2n s\u1ed1 1 v\u00e0 2 c\u00f3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 \u0111\u1ec1u kh\u00e1c nhau, t\u1ea1i sao hai ph\u00e2n s\u1ed1 n\u00e0y b\u1eb1ng nhau? 4 8 \u2192 Kh\u00e1m ph\u00e1 b\u00e0i h\u1ecdc h\u00f4m nay. 256","II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: Ph\u00e2n s\u1ed1 b\u1eb1ng nhau 1. Nh\u1eadn bi\u1ebft c\u00e1c ph\u00e2n s\u1ed1 21; 42; 3 b\u1eb1ng nhau qua th\u1ef1c h\u00e0nh 6 \u2013 HS \u0111i\u1ec3m danh 1, 2, 3, 1, 2, 3, \u2026 1 \u2013 C\u00e1c HS mang s\u1ed1 1: T\u00f4 m\u00e0u 2 b\u0103ng gi\u1ea5y. C\u00e1c HS mang s\u1ed1 2: T\u00f4 m\u00e0u 2 b\u0103ng gi\u1ea5y. 4 3 C\u00e1c HS mang s\u1ed1 3: T\u00f4 m\u00e0u 6 b\u0103ng gi\u1ea5y. \u2013 Sau khi t\u00f4 m\u00e0u, m\u1ed7i HS vi\u1ebft ph\u00e2n s\u1ed1 ch\u1ec9 ph\u1ea7n \u0111\u00e3 t\u00f4 m\u00e0u \u1edf b\u0103ng gi\u1ea5y c\u1ee7a m\u00ecnh. \u2013 Nh\u00f3m ba HS mang s\u1ed1 1, 2, 3 x\u1ebfp c\u00e1c b\u0103ng gi\u1ea5y nh\u01b0 ph\u1ea7n b\u00e0i h\u1ecdc \u1edf SGK. Nh\u1eadn x\u00e9t ph\u1ea7n \u0111\u00e3 t\u00f4 m\u00e0u: D\u00e0i b\u1eb1ng nhau. So s\u00e1nh ba ph\u00e2n s\u1ed1: 1 , 2 , 3 (b\u1eb1ng nhau). 2 4 6 1 2 2 3 1 3 GV vi\u1ebft b\u1ea3ng: 2 = 4 4 = 6 2 = 6 2. T\u00ecm hi\u1ec3u s\u1ef1 li\u00ean quan gi\u1eefa t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 \u1edf hai ph\u00e2n s\u1ed1 b\u1eb1ng nhau \u2013 GV vi\u1ebft b\u1ea3ng: \u00d72 :3 1 = 2 3= 1 2 4 62 \u00d7 .?. : .?. \u2013 HS nh\u1eadn bi\u1ebft s\u1ed1 \u0111\u1ec3 thay v\u00e0o .?.. 3. Kh\u00e1i qu\u00e1t t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1 \u2022 GV ch\u1ec9 v\u00e0o h\u00ecnh \u1ea3nh c\u00e1c c\u1eb7p ph\u00e2n s\u1ed1 b\u1eb1ng nhau gi\u00fap HS nh\u1eadn x\u00e9t: 1 1 2 2 \u2013 N\u1ebfu nh\u00e2n c\u1ea3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 c\u1ee7a ph\u00e2n s\u1ed1 2 v\u1edbi 2 th\u00ec \u0111\u01b0\u1ee3c ph\u00e2n s\u1ed1 4 b\u1eb1ng ph\u00e2n s\u1ed1 . \u2013 N\u1ebfu chia c\u1ea3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 c\u1ee7a ph\u00e2n s\u1ed1 3 cho 3 th\u00ec \u0111\u01b0\u1ee3c ph\u00e2n s\u1ed1 1 b\u1eb1ng ph\u00e2n s\u1ed1 3 . 6 2 6 \u2022 GV n\u00eau t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1 (SGK). N\u1ebfu c\u1ea7n th\u00ec GV c\u00f3 th\u1ec3 gi\u1ea3i th\u00edch th\u00eam: \u2013 N\u1ebfu nh\u00e2n m\u1eabu s\u1ed1 v\u1edbi 0 th\u00ec ph\u00e2n s\u1ed1 m\u1edbi c\u00f3 m\u1eabu s\u1ed1 l\u00e0 0. Ph\u00e2n s\u1ed1 n\u00e0y kh\u00f4ng x\u00e1c \u0111\u1ecbnh v\u00ec m\u1eabu s\u1ed1 c\u1ee7a m\u1ed9t ph\u00e2n s\u1ed1 lu\u00f4n kh\u00e1c 0. \u2013 Trong ph\u00e9p chia, s\u1ed1 chia ph\u1ea3i kh\u00e1c 0 n\u00ean kh\u00f4ng th\u1ec3 chia c\u1ea3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 cho 0. III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 HS th\u1ef1c hi\u00ean nh\u00f3m \u0111\u00f4i. \u2013 Khi s\u1eeda b\u00e0i, GV y\u00eau c\u1ea7u HS gi\u1ea3i th\u00edch. 257","Ch\u1eb3ng h\u1ea1n: 2 2 \u00d7 3 6 a) 3 = 3 \u00d7 3 = 9 T\u1eed s\u1ed1 ph\u1ea3i nh\u00e2n v\u1edbi 3 v\u00ec m\u1eabu s\u1ed1 \u0111\u00e3 nh\u00e2n v\u1edbi 3. 2 6 Ph\u00e2n s\u1ed1 3 b\u1eb1ng ph\u00e2n s\u1ed1 9 . \u2026 2. Luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, GV khuy\u1ebfn kh\u00edch HS gi\u1ea3i th\u00edch m\u1ed9t s\u1ed1 tr\u01b0\u1eddng h\u1ee3p. 7 1 V\u00ed d\u1ee5: ? = 2 T\u1eed s\u1ed1: t\u1eeb 7 xu\u1ed1ng 1 l\u00e0 gi\u1ea3m \u0111i 7 l\u1ea7n \u2192 M\u1eabu s\u1ed1: .?. gi\u1ea3m \u0111i 7 l\u1ea7n th\u00ec \u0111\u01b0\u1ee3c 2 \u2192 .?. = 2 \u00d7 7 = 14 7 1 Th\u1eed l\u1ea1i: 14 = 2 \t\t 7:7=1 \t\t 14 : 7 = 2 B\u00e0i 2: \u2013 HS th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, HS gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. 1 2 3 4 5 9 D\u1ef1a v\u00e0o ph\u00e2n s\u1ed1 2 \u0111\u1ec3 bi\u1ebft m\u1eabu s\u1ed1 c\u1ee7a c\u00e1c ph\u00e2n s\u1ed1 .?. ; .?. ; .?. ; .?. ; .?. \u0111\u01b0\u1ee3c t\u00ecm th\u1ebf n\u00e0o. B\u00e0i 3: \u2013 C\u00f3 th\u1ec3 th\u1ef1c hi\u1ec7n b\u1eb1ng c\u00e1ch giao vi\u1ec7c cho c\u00e1c nh\u00f3m GQV\u0110. \u2022 B\u01b0\u1edbc 1: T\u00ecm hi\u1ec3u v\u1ea5n \u0111\u1ec1 Nh\u1eadn bi\u1ebft v\u1ea5n \u0111\u1ec1 c\u1ea7n gi\u1ea3i quy\u1ebft: T\u00ecm c\u00e1c ph\u00e2n s\u1ed1 b\u1eb1ng nhau trong c\u00e1c ph\u00e2n s\u1ed1 \u0111\u00e3 cho. \u2022 B\u01b0\u1edbc 2: L\u1eadp k\u1ebf ho\u1ea1ch N\u00eau \u0111\u01b0\u1ee3c c\u00e1ch th\u1ee9c GQV\u0110 (c\u00f3 th\u1ec3 d\u00f9ng gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng \u0111\u1ec3 v\u1ebd v\u00e0 th\u1ec3 hi\u1ec7n c\u00e1c ph\u00e2n s\u1ed1, l\u01b0u \u00fd c\u00e1c b\u0103ng gi\u1ea5y d\u00e0i b\u1eb1ng nhau; c\u00f3 th\u1ec3 \u00e1p d\u1ee5ng t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1; \u2026). \u2022 B\u01b0\u1edbc 3: Ti\u1ebfn h\u00e0nh k\u1ebf ho\u1ea1ch HS th\u1ef1c hi\u1ec7n theo c\u00e1ch th\u1ee9c \u1edf B\u01b0\u1edbc 2. Tr\u00ecnh b\u00e0y tr\u01b0\u1edbc l\u1edbp. 2 6 3 9 \t 3 = 9 \t\t 4 = 12 \u2022 B\u01b0\u1edbc 4: Ki\u1ec3m tra l\u1ea1i C\u00f3 ph\u1ea3i c\u00f9ng nh\u00e2n ho\u1eb7c c\u00f9ng chia c\u1ea3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 v\u1edbi c\u00f9ng m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean kh\u00e1c 0? Th\u1ef1c hi\u1ec7n c\u00e1c ph\u00e9p t\u00ednh c\u00f3 \u0111\u00fang kh\u00f4ng? \u2013 S\u1eeda b\u00e0i, GV h\u1ec7 th\u1ed1ng c\u00e1ch \u00e1p d\u1ee5ng t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1 v\u00e0o c\u00e1c tr\u01b0\u1eddng h\u1ee3p c\u1ee7a b\u00e0i. Ch\u1eb3ng h\u1ea1n: 2 X\u00e9t ph\u00e2n s\u1ed1 3 258","T\u1eed s\u1ed1 (2) c\u00f3 th\u1ec3 nh\u00e2n v\u1edbi s\u1ed1 n\u00e0o \u0111\u1ec3 \u0111\u01b0\u1ee3c m\u1ed9t trong c\u00e1c t\u1eed s\u1ed1 c\u1ee7a c\u00e1c ph\u00e2n s\u1ed1 c\u00f2n l\u1ea1i? (2 \u00d7 3 = 6) 6 9 \u2192 X\u00e9t ph\u00e2n s\u1ed1 \u2192 M\u1eabu (3) c\u1ee7a ph\u00e2n s\u1ed1 2 khi nh\u00e2n v\u1edbi 3 b\u1eb1ng m\u1eabu (9) c\u1ee7a ph\u00e2n s\u1ed1 6 3 9 \u2192 K\u1ebft lu\u1eadn 2 = 6 . \u2026 3 9 IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 4: a) \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n. \u2013 Sau khi s\u1eeda b\u00e0i, GV h\u01b0\u1edbng d\u1eabn HS nh\u1eadn ra t\u00ednh ch\u1ea5t c\u1ee7a ph\u00e9p chia. N\u1ebfu c\u00f9ng g\u1ea5p ho\u1eb7c c\u00f9ng gi\u1ea3m s\u1ed1 b\u1ecb chia v\u00e0 s\u1ed1 chia m\u1ed9t s\u1ed1 l\u1ea7n th\u00ec th\u01b0\u01a1ng kh\u00f4ng thay \u0111\u1ed5i. \u00d72 :6 S\u1ed1 b\u1ecb chia 24 48 8 S\u1ed1 chia 6 .?. .?. Th\u01b0\u01a1ng 4 4 4 b) \u2013 HS th\u1ef1c hi\u1ec7n nh\u00f3m b\u1ed1n. \u2013 Khi s\u1eeda b\u00e0i, GV c\u00f3 th\u1ec3 d\u00f9ng m\u00f4 h\u00ecnh gi\u00fap HS nh\u1eadn bi\u1ebft vi\u1ec7c \u00e1p d\u1ee5ng t\u00ednh ch\u1ea5t c\u1ee7a ph\u00e9p chia \u0111\u1ec3 th\u1ef1c hi\u1ec7n. S\u1ed1 b\u00e1nh : S\u1ed1 h\u1ed9p = S\u1ed1 b\u00e1nh m\u1ed7i h\u1ed9p \u2013 Trong ph\u00e9p chia n\u00e0y, c\u00e1i g\u00ec kh\u00f4ng thay \u0111\u1ed5i? (th\u01b0\u01a1ng: m\u1ed7i h\u1ed9p 4 c\u00e1i b\u00e1nh) \u2013 Th\u00e0nh ph\u1ea7n n\u00e0o thay \u0111\u1ed5i? (s\u1ed1 b\u1ecb chia g\u1ea5p l\u00ean 2 l\u1ea7n) \u2013 \u0110\u1ec3 th\u01b0\u01a1ng kh\u00f4ng \u0111\u1ed5i, s\u1ed1 chia ph\u1ea3i th\u1ebf n\u00e0o? (g\u1ea5p l\u00ean 2 l\u1ea7n) C\u0169ng c\u00f3 th\u1ec3 d\u00f9ng m\u00f4 h\u00ecnh sau \u0111\u1ec3 gi\u1ea3i th\u00edch. \t\t\t S\u1ed1 b\u1ecb chia = Th\u01b0\u01a1ng S\u1ed1 chia B\u00e0i 5: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n r\u1ed3i s\u1eeda b\u00e0i d\u01b0\u1edbi d\u1ea1ng tr\u00f2 ch\u01a1i thi \u0111ua. \u2013 HS gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. \u2022 H\u00ecnh 1 v\u00e0 H\u00ecnh 3, m\u1ed7i h\u00ecnh c\u00f3 3 h\u00e0ng, t\u00f4 m\u00e0u 2 h\u00e0ng. \u2022 H\u00ecnh 4 c\u00f3 3 c\u1ed9t, t\u00f4 m\u00e0u 2 c\u1ed9t. 2 V\u1eady 3 c\u1ee7a h\u00ecnh 1, 3, 4 \u0111\u01b0\u1ee3c t\u00f4 m\u00e0u. 259","Vui h\u1ecdc a) B\u1ee9c t\u01b0\u1eddng th\u1ee9 nh\u1ea5t: \u2013 C\u00f3 t\u1ea5t c\u1ea3 30 vi\u00ean g\u1ea1ch, trong \u0111\u00f3 c\u00f3 10 vi\u00ean g\u1ea1ch m\u00e0u xanh. 1300. \u2013 Ph\u00e2n s\u1ed1 ch\u1ec9 s\u1ed1 g\u1ea1ch m\u00e0u xanh tr\u00ean b\u1ee9c t\u01b0\u1eddng th\u1ee9 nh\u1ea5t l\u00e0 B\u1ee9c t\u01b0\u1eddng th\u1ee9 hai: \u2013 C\u00f3 t\u1ea5t c\u1ea3 15 vi\u00ean g\u1ea1ch, trong \u0111\u00f3 c\u00f3 5 vi\u00ean g\u1ea1ch m\u00e0u xanh. 155. \u2013 Ph\u00e2n s\u1ed1 ch\u1ec9 s\u1ed1 g\u1ea1ch m\u00e0u xanh tr\u00ean b\u1ee9c t\u01b0\u1eddng th\u1ee9 hai l\u00e0 2 th\u00ec 10 5 b) Hai ph\u00e2n s\u1ed1 30 v\u00e0 15 b\u1eb1ng nhau v\u00ec: 10 5 s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 c\u1ee7a 30 15 \u2013 Khi ta c\u00f9ng chia c\u1ea3 t\u1eed ph\u00e2n s\u1ed1 cho ta \u0111\u01b0\u1ee3c ph\u00e2n s\u1ed1 b\u1eb1ng ph\u00e2n s\u1ed1 3100. Hay 5 10 \u2013 Khi ta c\u00f9ng nh\u00e2n c\u1ea3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 c\u1ee7a ph\u00e2n s\u1ed1 15 v\u1edbi 2 th\u00ec ta \u0111\u01b0\u1ee3c ph\u00e2n s\u1ed1 30 b\u1eb1ng ph\u00e2n s\u1ed1 155. B\u00e0i 63. R\u00daT G\u1eccN PH\u00c2N S\u1ed0 (2 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS nh\u1eadn bi\u1ebft vi\u1ec7c v\u1eadn d\u1ee5ng t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1 \u0111\u1ec3 r\u00fat g\u1ecdn ph\u00e2n s\u1ed1, th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c vi\u1ec7c r\u00fat g\u1ecdn ph\u00e2n s\u1ed1 trong nh\u1eefng tr\u01b0\u1eddng h\u1ee3p \u0111\u01a1n gi\u1ea3n (s\u1eed d\u1ee5ng c\u00e1c b\u1ea3ng nh\u00e2n, chia; c\u00e1c d\u1ea1ng nh\u00e2n, chia nh\u1ea9m \u0111\u00e3 h\u1ecdc). \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn vi\u1ec7c r\u00fat g\u1ecdn ph\u00e2n s\u1ed1. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t ch\u0103m ch\u1ec9, y\u00eau n\u01b0\u1edbc. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh c\u00f3 trong b\u00e0i (n\u1ebfu c\u1ea7n). C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng GV gi\u1edbi thi\u1ec7u h\u00ecnh \u1ea3nh nh\u1eefng l\u00e1 c\u1edd. 260","Giao vi\u1ec7c cho c\u00e1c nh\u00f3m. \u2013 Vi\u1ec7c 1: Vi\u1ebft ph\u00e2n s\u1ed1 ch\u1ec9 s\u1ed1 l\u00e1 c\u1edd m\u00e0u \u0111\u1ecf \u1edf h\u00ecnh \u1ea3nh tr\u00ean b\u1ea3ng. m\u1eabH\u2013Cu \u00e1VsSc\u1ed1iv\u1ec7nbic\u1ebfh\u00e9t2\u00f3:h:m11\u01a1V82n\u1eadGnvnQ\u00e0dhgV\u1ee5\u01b0inn\u1ea3\u0110igg.tnphhh\u00edc\u1eef\u00e2hnn(gsc\u1ed1h\u00f3imt\u1ec3\u1ea5u\u1edbt ibc\u1ea3vi\u1ebf\u1eab1tn8v\u1ec1bl\u00e1\u1eb1pnchg\u1edd\u00e2,npthrso\u1ed1\u00e2nn, vgsi\u1ed1\u1ebf\u0111t\u00f311p28ch.\u00f3\u00e2n12s\u1ed1l\u00e111c82\u1eddtmh\u00e0\u00e0nuh\u0111p\u1ecfh)\u00e2. n s\u1ed1 c\u00f3 t\u1eed s\u1ed1 v\u00e0 \u2022 B\u01b0\u1edbc 1: T\u00ecm hi\u1ec3u v\u1ea5n \u0111\u1ec1 12 18 \u2013 Nh\u1eadn bi\u1ebft v\u1ea5n \u0111\u1ec1 c\u1ea7n gi\u1ea3i quy\u1ebft: Vi\u1ebft ph\u00e2n s\u1ed1 th\u00e0nh ph\u00e2n s\u1ed1 c\u00f3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 b\u00e9 1182. h\u01a1n nh\u01b0ng ph\u00e2n s\u1ed1 m\u1edbi v\u1eabn b\u1eb1ng ph\u00e2n s\u1ed1 B\u01b0\u1edbc 2: L\u1eadp k\u1ebf ho\u1ea1ch N\u00eau \u0111\u01b0\u1ee3c c\u00e1ch th\u1ee9c GQV\u0110 (c\u00f3 th\u1ec3 d\u00f9ng h\u00ecnh \u1ea3nh: v\u1ebd l\u1ea1i c\u00e1c l\u00e1 c\u1edd theo ba nh\u00f3m; c\u00f3 th\u1ec3 \u00e1p d\u1ee5ng t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1; \u2026). \u2022 B\u01b0\u1edbc 3: Ti\u1ebfn h\u00e0nh k\u1ebf ho\u1ea1ch HS th\u1ef1c hi\u1ec7n theo c\u00e1ch th\u1ee9c \u1edf B\u01b0\u1edbc 2. Tr\u00ecnh b\u00e0y tr\u01b0\u1edbc l\u1edbp. 12 2 18 = 3 (c\u00f3 gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m) \u2022 B\u01b0\u1edbc 4: Ki\u1ec3m tra l\u1ea1i X\u00e1c t\u00edn xem ph\u00e2n s\u1ed1 m\u1edbi t\u00ecm c\u00f3 tho\u1ea3 m\u00e3n hai y\u00eau c\u1ea7u: 2 12 Ph\u00e2n s\u1ed1 3 c\u00f3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 b\u00e9 h\u01a1n ph\u00e2n s\u1ed1 18 kh\u00f4ng? 11PG82hV\u00e2mng\u00e0is\u1edbg\u1ed1iit\u00e132hticr\u1ec7\u00f3\u1ecbup:bhT\u1eb1\u00e2anng\u0111s\u00e3p\u1ed1hckh\u00e2hnu\u00f4ys\u1ec3n\u1ed1ng11pt28hhak\u00e2yhn\u00f4\u0111sn\u1ed5\u1ed1ig,11?v28i\u1ec7thc\u00e0l\u00e0nmh pnh\u00e0\u00e2yngs\u1ecd\u1ed1i 2 c\u00f3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 b\u00e9 h\u01a1n ph\u00e2n 3 r\u00fat g\u1ecdn ph\u00e2n s\u1ed1. s\u1ed1 l\u00e0 GV c\u00f3 th\u1ec3 s\u1eafp x\u1ebfp l\u1ea1i h\u00ecnh \u1ea3nh nh\u1eefng l\u00e1 c\u1edd 2 ho\u1eb7c v\u1ebd th\u00eam \u0111\u01b0\u1eddng k\u1ebb th\u1ec3 hi\u1ec7n ph\u00e2n s\u1ed1 3 \u2192 Gi\u1edbi thi\u1ec7u b\u00e0i m\u1edbi. II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: R\u00fat g\u1ecdn ph\u00e2n s\u1ed1 1. Gi\u1edbi thi\u1ec7u c\u00e1ch tr\u00ecnh b\u00e0y b\u00e0i r\u00fat g\u1ecdn ph\u00e2n s\u1ed1 \u2013 GV v\u1ea5n \u0111\u00e1p \u0111\u1ec3 HS x\u00e2y d\u1ef1ng b\u00e0i, GV h\u01b0\u1edbng d\u1eabn c\u00e1ch tr\u00ecnh b\u00e0y, HS vi\u1ebft theo. C\u00e1ch 1 T\u1eed s\u1ed1 (12) v\u00e0 m\u1eabu s\u1ed1 (18) c\u00f9ng chia h\u1ebft cho s\u1ed1 n\u00e0o? (2) \tTa chia\tc\u1ea3 t\u1eed s\u1ed1\tv\u00e0 m\u1eab\tu s\u1ed1 ch\to 2. 1128 = 12 : 2 = 6 18 : 2 9 261","T\u1eed s\u1ed1 (6) v\u00e0 m\u1eabu s\u1ed1 (9) c\u00f9ng chia h\u1ebft cho s\u1ed1 n\u00e0o? (3) Ta chia c\u1ea3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 cho 3. 6 6:3 2 9 9:3 3 \t\t\t\t\t = = T\u1eed s\u1ed1 (2) v\u00e0 m\u1eabu s\u1ed1 (3) c\u00f3 c\u00f9ng chia h\u1ebft cho s\u1ed1 n\u00e0o kh\u00f4ng? (kh\u00f4ng) 2 2 v\u00e0 3 kh\u00f4ng c\u00f9ng chia h\u1ebft cho s\u1ed1 n\u00e0o l\u1edbn h\u01a1n 1, ta n\u00f3i 3 l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. N\u1ebfu l\u1ec7nh c\u1ee7a b\u00e0i l\u00e0 R\u00fat g\u1ecdn th\u00ec k\u1ebft qu\u1ea3 ph\u1ea3i l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n (kh\u00f4ng th\u1ec3 r\u00fat g\u1ecdn \u0111\u01b0\u1ee3c n\u1eefa). L\u01b0u \u00fd: \u2022 C\u00f3 th\u1ec3 r\u00fat g\u1ecdn cho 3 tr\u01b0\u1edbc, 2 sau. \u2022 GV nh\u1eafc nh\u1edf nh\u1eefng HS tr\u00ecnh b\u00e0y sai do th\u00f3i quen. C\u00e1ch 2 T\u1eed s\u1ed1 (12) v\u00e0 m\u1eabu s\u1ed1 (18) c\u00f9ng chia h\u1ebft cho s\u1ed1 n\u00e0o ngo\u00e0i 2 v\u00e0 3? (6) Ta chia c\u1ea3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 cho 6. 12 6 2 \t\t\t\t\t1128 18 6 3 = : = : 2. Kh\u00e1i qu\u00e1t ho\u00e1 c\u00e1ch r\u00fat g\u1ecdn ph\u00e2n s\u1ed1 GV g\u1ee3i \u00fd, gi\u00fap HS \u0111\u01b0a ra c\u00e1ch r\u00fat g\u1ecdn. \u2013 Xem t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 c\u00f3 c\u00f9ng chia h\u1ebft cho s\u1ed1 t\u1ef1 nhi\u00ean n\u00e0o l\u1edbn h\u01a1n 1 kh\u00f4ng. \u2013 Chia t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 cho s\u1ed1 \u0111\u00f3. C\u1ee9 l\u00e0m nh\u01b0 th\u1ebf cho \u0111\u1ebfn khi nh\u1eadn \u0111\u01b0\u1ee3c ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 GV l\u01b0u \u00fd HS: \u2022 Khi t\u00ecm c\u00e1c s\u1ed1 \u0111\u1ec3 r\u00fat g\u1ecdn, ng\u01b0\u1eddi ta th\u01b0\u1eddng \u0111\u1ec3 \u00fd c\u00e1c tr\u01b0\u1eddng h\u1ee3p \u0111\u1eb7c bi\u1ec7t: S\u1ed1 chia h\u1ebft cho 2 (s\u1ed1 ch\u1eb5n). S\u1ed1 chia h\u1ebft cho 5 (s\u1ed1 c\u00f3 t\u1eadn c\u00f9ng l\u00e0 0 ho\u1eb7c 5). S\u1ed1 chia h\u1ebft cho 10 (s\u1ed1 c\u00f3 t\u1eadn c\u00f9ng l\u00e0 0). C\u00e1c tr\u01b0\u1eddng h\u1ee3p chia h\u1ebft cho 3, 4, 6, 7, 8, 9: V\u1eadn d\u1ee5ng b\u1ea3ng nh\u00e2n, b\u1ea3ng chia. \u2022 C\u00e1ch tr\u00ecnh b\u00e0y. \u2022 K\u1ebft qu\u1ea3 ph\u1ea3i l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. 2. Luy\u1ec7n t\u1eadp B\u00e0i 1: Th\u1ef1c hi\u1ec7n t\u01b0\u01a1ng t\u1ef1 b\u00e0i Th\u1ef1c h\u00e0nh 1. \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. 262","B\u00e0i 2: \u2013 HS t\u00ecm hi\u1ec3u b\u00e0i, nh\u1eadn bi\u1ebft c\u00e1c ph\u00e2n s\u1ed1 ch\u01b0a t\u1ed1i gi\u1ea3n v\u00e0 r\u00fat g\u1ecdn c\u00e1c ph\u00e2n s\u1ed1 \u0111\u00f3. 15 30 30 \u2013 C\u00e1c ph\u00e2n s\u1ed1 c\u1ea7n r\u00fat g\u1ecdn: 9 , 80 , 45 . B\u00e0i 3: \u2013 HS t\u00ecm hi\u1ec3u b\u00e0i, th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i. 3 = 3 \u00d7 2 = 6 \t \t\t 15 = 15 : 3 = 5 \t 4 4 \u00d7 2 8 9 9:3 3 15 = 15 : 15 = 1 \t\t\t 42 = 42 : 7 = 6 60 60 : 15 4 56 56 : 7 8 C\u00e1c ph\u00e2n s\u1ed1 b\u1eb1ng 6 l\u00e0 3 v\u00e0 42 . 8 4 56 IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c s\u1eeda b\u00e0i th\u00e0nh c\u00e1c tr\u00f2 ch\u01a1i thi \u0111ua. Th\u1eed th\u00e1ch S\u1eeda b\u00e0i, GV l\u01b0u \u00fd HS: .?. C\u00e2u n\u00f3i .?. s\u1ed1 qu\u1ea3 m\u0103ng c\u1ee5t n\u1eb1m tr\u00ean \u0111\u0129a c\u00f3 ngh\u0129a: X\u00e1c \u0111\u1ecbnh ph\u00e2n s\u1ed1 ch\u1ec9 s\u1ed1 qu\u1ea3 m\u0103ng c\u1ee5t n\u1eb1m tr\u00ean \u0111\u0129a trong t\u1ed5ng s\u1ed1 qu\u1ea3 m\u0103ng c\u1ee5t (kh\u00f4ng \u0111\u1ec3 \u00fd t\u1edbi nh\u1eefng qu\u1ea3 chu\u1ed1i). Do 6 = 2 n\u00ean 2 s\u1ed1 qu\u1ea3 m\u0103ng c\u1ee5t n\u1eb1m tr\u00ean \u0111\u0129a. 9 3 3 \u0110\u1ea5t n\u01b0\u1edbc em \u2013 Vi\u1ebft ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n ch\u1ec9 s\u1ed1 t\u1ec9nh v\u00e0 th\u00e0nh ph\u1ed1 c\u00f3 bi\u1ec3n tr\u00ean c\u1ea3 n\u01b0\u1edbc t\u1ee9c l\u00e0 vi\u1ebft ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n ch\u1ec9 28 t\u1ec9nh, th\u00e0nh ph\u1ed1 tr\u00ean 63 t\u1ec9nh, th\u00e0nh c\u1ea3 n\u01b0\u1edbc. \t\t\t\t6283 = 28 : 7 = 4 63 : 7 9 V\u1eady 4 l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n ch\u1ec9 s\u1ed1 t\u1ec9nh v\u00e0 th\u00e0nh ph\u1ed1 c\u00f3 bi\u1ec3n tr\u00ean c\u1ea3 n\u01b0\u1edbc. 9 \u2013 Khi m\u1ed9t HS n\u00eau t\u00ean m\u1ed9t t\u1ec9nh, th\u00e0nh ph\u1ed1 c\u00f3 bi\u1ec3n, GV gi\u00fap c\u00e1c em t\u00ecm tr\u00ean b\u1ea3n \u0111\u1ed3 (trang 81) \u0111\u1ec3 ki\u1ec3m tra xem c\u00f3 \u0111\u00fang kh\u00f4ng. 263","B\u00e0i 64. EM L\u00c0M \u0110\u01af\u1ee2C NH\u1eeeNG G\u00cc? (2 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c vi\u1ec7c t\u00ecm ph\u00e2n s\u1ed1 b\u1eb1ng ph\u00e2n s\u1ed1 \u0111\u00e3 cho nh\u1edd \u00e1p d\u1ee5ng t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1, r\u00fat g\u1ecdn ph\u00e2n s\u1ed1. \u2013 V\u1eadn d\u1ee5ng \u0111\u1ec3 gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn c\u00e1c ki\u1ebfn th\u1ee9c \u0111\u00e3 h\u1ecdc v\u1ec1 ph\u00e2n s\u1ed1 v\u00e0 bi\u1ec3u \u0111\u1ed3. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t ch\u0103m ch\u1ec9, tr\u00e1ch nhi\u1ec7m. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh c\u00f3 trong b\u00e0i (n\u1ebfu c\u1ea7n). C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ch\u01a1i tr\u00f2 ch\u01a1i \u201cT\u00f4i b\u1ea3o\u201d. \u2013 GV: T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? \u2013 GV: T\u00f4i b\u1ea3o c\u00e1c b\u1ea1n n\u00f3i c\u00e1ch r\u00fat g\u1ecdn ph\u00e2n s\u1ed1. \u2013 HS: Chia c\u1ea3 t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1 cho c\u00f9ng m\u1ed9t s\u1ed1 t\u1ef1 nhi\u00ean l\u1edbn h\u01a1n 1. \u2013 GV: T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? \u2013 GV: T\u00f4i b\u1ea3o c\u00e1c b\u1ea1n cho bi\u1ebft k\u1ebft qu\u1ea3 c\u1ee7a vi\u1ec7c r\u00fat g\u1ecdn l\u00e0 ph\u00e2n s\u1ed1 d\u1ea1ng n\u00e0o? \u2013 HS: Ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. II. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 Khi s\u1eeda b\u00e0i, HS gi\u1ea3i th\u00edch t\u1ea1i sao t\u00ecm \u0111\u01b0\u1ee3c s\u1ed1 \u0111\u00f3. Khuy\u1ebfn kh\u00edch vi\u1ec7c th\u1eed l\u1ea1i. B\u00e0i 2: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 GV y\u00eau c\u1ea7u HS nh\u1eafc l\u1ea1i nh\u1eefng l\u01b0u \u00fd khi l\u00e0m b\u00e0i r\u00fat g\u1ecdn. \u2022 Khi t\u00ecm c\u00e1c s\u1ed1 \u0111\u1ec3 r\u00fat g\u1ecdn, ng\u01b0\u1eddi ta th\u01b0\u1eddng \u0111\u1ec3 \u00fd c\u00e1c tr\u01b0\u1eddng h\u1ee3p \u0111\u1eb7c bi\u1ec7t: S\u1ed1 chia h\u1ebft cho 2 (s\u1ed1 ch\u1eb5n). S\u1ed1 chia h\u1ebft cho 5 (s\u1ed1 c\u00f3 t\u1eadn c\u00f9ng l\u00e0 0 ho\u1eb7c 5). S\u1ed1 chia h\u1ebft cho 10 (s\u1ed1 c\u00f3 t\u1eadn c\u00f9ng l\u00e0 0). C\u00e1c tr\u01b0\u1eddng h\u1ee3p chia h\u1ebft cho 3, 4, 6, 7, 8, 9: V\u1eadn d\u1ee5ng b\u1ea3ng nh\u00e2n, b\u1ea3ng chia. \u2022 C\u00e1ch tr\u00ecnh b\u00e0y. \u2022 K\u1ebft qu\u1ea3 ph\u1ea3i l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. 264","B\u00e0i 3: \u2013 HS th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. \u2013 HS c\u00f3 th\u1ec3 th\u1ef1c hi\u1ec7n theo c\u00e1c c\u00e1ch: \u2022 D\u1ef1a v\u00e0o s\u1ed1 \u00f4 vu\u00f4ng, vi\u1ebft ph\u00e2n s\u1ed1 r\u1ed3i r\u00fat g\u1ecdn. \u2022 D\u1ef1a v\u00e0o m\u00e0u vi\u1ebft ngay ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. V\u00ed d\u1ee5: a) C\u00e1ch 1: \t132 \t 3 = 3:3 = 1 \t 12 12 : 3 4 C\u00e1ch 2: \tH\u00ecnh ch\u1eef nh\u1eadt chia th\u00e0nh 4 c\u1ed9t b\u1eb1ng nhau, t\u00f4 m\u00e0u 1 c\u1ed9t. 1 \tPh\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n ch\u1ec9 ph\u1ea7n t\u00f4 m\u00e0u l\u00e0 4 . \u2026 III. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 4: \u2013 HS th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, GV y\u00eau c\u1ea7u HS gi\u1ea3i th\u00edch. a) H\u00ecnh 1: 6 ; H\u00ecnh 2: 9 ; H\u00ecnh 3: 6 ; H\u00ecnh 4: 8 . 9 15 10 12 b) Sau khi r\u00fat g\u1ecdn, ta \u0111\u01b0\u1ee3c c\u00e1c ph\u00e2n s\u1ed1: 23 3 2 35 5 3 6 8 2 Ta c\u00f3 9 = 12 (v\u00ec c\u00f9ng b\u1eb1ng 3 ); 9 = 6 (v\u00ec c\u00f9ng b\u1eb1ng 3 ). 15 10 5 L\u01b0u \u00fd: C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c cho c\u00e1c nh\u00f3m b\u1ed1n HS GQV\u0110. B\u00e0i 5: \u2013 HS th\u1ef1c hi\u1ec7n nh\u00f3m b\u1ed1n. L\u01b0u \u00fd: HS \u0111\u1ecdc \u0111\u1ec1 th\u1eadt k\u0129. \u2013 S\u1eeda b\u00e0i, GV khuy\u1ebfn kh\u00edch HS gi\u1ea3i th\u00edch: S\u1ed1 t\u1ef1 nhi\u00ean l\u1edbn nh\u1ea5t c\u00f3 m\u1ed9t ch\u1eef s\u1ed1 l\u00e0 9. S\u1ed1 t\u1ef1 nhi\u00ean b\u00e9 nh\u1ea5t c\u00f3 hai ch\u1eef s\u1ed1 l\u00e0 10. 9 Vi\u1ebft ph\u00e2n s\u1ed1: 10 . 10 chia h\u1ebft cho c\u00e1c s\u1ed1 l\u1edbn h\u01a1n 1 l\u00e0: 2, 5 v\u00e0 10. 9 kh\u00f4ng chia h\u1ebft cho 2, 5 v\u00e0 10. 9 V\u1eady 10 l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. 265","B\u00e0i 6: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. \u2013 S\u1eeda b\u00e0i, GV y\u00eau c\u1ea7u HS gi\u1ea3i th\u00edch. 2 3 C\u00f3 th\u1ec3 gi\u1ea3i th\u00edch nh\u01b0 sau: C\u00e1c ph\u00e2n s\u1ed1 n\u00e0y sau khi r\u00fat g\u1ecdn \u0111\u1ec1u b\u1eb1ng . Th\u1eed th\u00e1ch HS c\u00f3 th\u1ec3 d\u1ef1a v\u00e0o h\u00ecnh \u1ea3nh \u0111\u1ed3ng h\u1ed3 \u0111\u1ec3 gi\u1ea3i th\u00edch. H\u00ecnh A: 1 gi\u1edd\t\t\t H\u00ecnh B: 1 gi\u1edd 4 2 3 H\u00ecnh C: 4 gi\u1edd\t\t\t H\u00ecnh D: 1 gi\u1edd B\u00e0i 65. QUY \u0110\u1ed2NG M\u1eaaU S\u1ed0 C\u00c1C PH\u00c2N S\u1ed0 (2 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c quy \u0111\u1ed3ng m\u1eabu s\u1ed1 hai ph\u00e2n s\u1ed1 trong tr\u01b0\u1eddng h\u1ee3p c\u00f3 m\u1ed9t m\u1eabu s\u1ed1 chia h\u1ebft cho m\u1eabu s\u1ed1 c\u00f2n l\u1ea1i. \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn vi\u1ec7c quy \u0111\u1ed3ng m\u1eabu s\u1ed1. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t ch\u0103m ch\u1ec9, tr\u00e1ch nhi\u1ec7m. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: H\u00ecnh \u1ea3nh cho ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng (n\u1ebfu c\u1ea7n). C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng GV h\u01b0\u1edbng d\u1eabn HS t\u00ecm hi\u1ec3u ph\u1ea7n kh\u1edfi \u0111\u1ed9ng. \u2013 B\u1ea1n th\u1ee9 nh\u1ea5t n\u00f3i g\u00ec? (Tr\u1ed3ng hoa c\u00fac tr\u00ean 1 m\u1ea3nh \u0111\u1ea5t.) 4 GV cho HS quan s\u00e1t h\u00ecnh \u1ea3nh. 266","\u2013 B\u1ea1n th\u1ee9 hai n\u00f3i g\u00ec? (Tr\u1ed3ng hoa h\u1ed3ng tr\u00ean 3 m\u1ea3nh \u0111\u1ea5t.) 8 GV cho HS quan s\u00e1t h\u00ecnh \u1ea3nh. \u2013 V\u1eabn m\u1ea3nh \u0111\u1ea5t \u0111\u00f3 nh\u01b0ng c\u00e1ch chia th\u00e0nh c\u00e1c ph\u1ea7n b\u1eb1ng nhau l\u1ea1i kh\u00e1c. Theo em, ta s\u1ebd chia m\u1ea3nh \u0111\u1ea5t th\u1ebf n\u00e0o \u0111\u1ec3 thu\u1eadn ti\u1ec7n cho vi\u1ec7c th\u1ec3 hi\u1ec7n c\u00e1c ph\u1ea7n tr\u1ed3ng hoa? (8 ph\u1ea7n b\u1eb1ng nhau) GV cho HS quan s\u00e1t h\u00ecnh \u1ea3nh. \u2013 Vi\u1ebft ph\u00e2n s\u1ed1 ch\u1ec9 ph\u1ea7n tr\u1ed3ng hoa c\u00fac trong tr\u01b0\u1eddng h\u1ee3p m\u1ea3nh \u0111\u1ea5t \u0111\u01b0\u1ee3c chia th\u00e0nh 8 ph\u1ea7n 2 b\u1eb1ng nhau. ( 8 ) \u2013 L\u00fac \u0111\u1ea7u hai ph\u00e2n s\u1ed1 1 v\u00e0 3 c\u00f3 m\u1eabu s\u1ed1 kh\u00e1c nhau. 4 8 2 3 L\u00fac sau hai ph\u00e2n s\u1ed1 8 v\u00e0 8 c\u00f3 m\u1eabu s\u1ed1 b\u1eb1ng nhau. Ta \u0111\u00e3 quy \u0111\u1ed3ng m\u1eabu s\u1ed1 hai ph\u00e2n s\u1ed1 (l\u00e0m cho hai m\u1eabu s\u1ed1 b\u1eb1ng nhau m\u00e0 gi\u00e1 tr\u1ecb ph\u00e2n s\u1ed1 kh\u00f4ng thay \u0111\u1ed5i). \u2192 Gi\u1edbi thi\u1ec7u b\u00e0i m\u1edbi. II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 c\u00e1c ph\u00e2n s\u1ed1 1. Gi\u1edbi thi\u1ec7u c\u00e1ch tr\u00ecnh b\u00e0y vi\u1ec7c quy \u0111\u1ed3ng m\u1eabu s\u1ed1 1 3 \u2022 V\u00ed d\u1ee5 1: Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 hai ph\u00e2n s\u1ed1 4 v\u00e0 8 . \u2013 \u0110\u1ec3 l\u00e0m cho m\u1eabu s\u1ed1 c\u1ee7a hai ph\u00e2n s\u1ed1 gi\u1ed1ng nhau (ta g\u1ecdi l\u00e0 m\u1eabu s\u1ed1 chung), n\u00ean ch\u1ecdn m\u1eabu s\u1ed1 chung l\u00e0 s\u1ed1 n\u00e0o? (8) \u2013 V\u00ec sao l\u1ea1i ch\u1ecdn 8 l\u00e0 m\u1eabu s\u1ed1 chung? (8 chia h\u1ebft cho 4) \u2013 H\u00e3y vi\u1ebft ph\u00e2n s\u1ed1 1 d\u01b0\u1edbi d\u1ea1ng ph\u00e2n s\u1ed1 c\u00f3 m\u1eabu s\u1ed1 l\u00e0 8 (l\u01b0u \u00fd tr\u00ecnh b\u00e0y \u0111\u01b0\u1ee3c c\u00e1ch \u00e1p 4 d\u1ee5ng t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1). 1 1 \u00d72 2 \t\t\t\t\t 4 = 4 \u00d72 = 8 \t \u2013 Sau khi quy \u0111\u1ed3ng m\u1eabu s\u1ed1, ta \u0111\u01b0\u1ee3c hai ph\u00e2n s\u1ed1 n\u00e0o? ( 2 v\u00e0 3 ) 8 8 \u2013 GV vi\u1ebft l\u00ean b\u1ea3ng: \t\t\t\t\t 2 v\u00e0 3 8 8 267","\u2022 V\u00ed d\u1ee5 2: Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 hai ph\u00e2n s\u1ed1 2 v\u00e0 5 . 3 12 \u2013 HS (nh\u00f3m b\u1ed1n) th\u1ea3o lu\u1eadn, t\u00ecm c\u00e1ch th\u1ef1c hi\u1ec7n. \u2013 GV c\u00f3 th\u1ec3 g\u1ee3i \u00fd: Ta n\u00ean ch\u1ecdn m\u1eabu s\u1ed1 chung l\u00e0 s\u1ed1 n\u00e0o? (12) \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, r\u1ed3i chia s\u1ebb v\u1edbi b\u1ea1n trong nh\u00f3m. \u2013 S\u1eeda b\u00e0i, HS tr\u00ecnh b\u00e0y tr\u00ean b\u1ea3ng l\u1edbp, gi\u1ea3i th\u00edch l\u00ed do ch\u1ecdn m\u1eabu s\u1ed1 chung ta \u0111\t\tV\u01b0\u00ed\u1ee3dc\u1ee5p: hV\t\t\u00e2\u00ecn1s2\u1ed1cmh\t\ti\u1edbaihc\u1ebf\u00f3t cm\t\th\u1eabou3s\u2192\u1ed1 g\t\t1i\u1ed12n:g3m=1328\u1eab24u=v\u2192s\u00e023\u1ed11\u00d7\u00d7Nc52\u1ee7h44a.\u00e2=pnhc1\u00e28\u1ea32\tnt\u1eeds\u1ed1s\u1ed1152v\u00e0v\u00e0mb\u1eab\u1eb1unsg\u1ed1vc\u1edb\u1ee7iapphh\u00e2n\u00e2ns\u1ed1s\u1ed13232: v\u1edbi 4, 2. Kh\u00e1i qu\u00e1t ho\u00e1 c\u00e1ch quy \u0111\u1ed3ng m\u1eabu s\u1ed1 hai ph\u00e2n s\u1ed1 GV h\u1ecfi \u0111\u1ec3 HS x\u00e2y d\u1ef1ng \u0111\u01b0\u1ee3c quy t\u1eafc. Khi quy \u0111\u1ed3ng m\u1eabu s\u1ed1 hai ph\u00e2n s\u1ed1, ta c\u00f3 th\u1ec3 l\u00e0m nh\u01b0 sau: \u2013 T\u00ecm m\u1eabu s\u1ed1 chung (GV gi\u1ea3i th\u00edch: th\u01b0\u1eddng l\u00e0 s\u1ed1 l\u1edbn). \u2013 \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n c\u1ee7a ph\u00e2n s\u1ed1, vi\u1ebft ph\u00e2n s\u1ed1 c\u00f2n l\u1ea1i th\u00e0nh ph\u00e2n s\u1ed1 c\u00f3 m\u1eabu s\u1ed1 l\u00e0 m\u1eabu s\u1ed1 chung. III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 GV n\u00ean th\u1ed1ng nh\u1ea5t c\u00e1ch tr\u00ecnh b\u00e0y. Ch\u1eb3ng h\u1ea1n: a) 3 v\u00e0 5 2 6 3 = 3\u00d7 3 = 69\t 2 2\u00d7 3 9 v\u00e0 5 6 6 \u2026 \u2013 Khuy\u1ebfn kh\u00edch HS th\u1eed l\u1ea1i sau khi quy \u0111\u1ed3ng m\u1eabu s\u1ed1 (b\u1eb1ng c\u00e1ch r\u00fat g\u1ecdn). \u2013 S\u1eeda b\u00e0i, GV khuy\u1ebfn kh\u00edch HS gi\u1ea3i th\u00edch: \u1ede t\u1eed s\u1ed1, t\u1ea1i sao l\u1ea5y 3 nh\u00e2n v\u1edbi 3? (M\u1eabu s\u1ed1 2 ph\u1ea3i nh\u00e2n v\u1edbi 3 \u0111\u1ec3 \u0111\u01b0\u1ee3c m\u1eabu chung l\u00e0 6 n\u00ean t\u1eed s\u1ed1 c\u0169ng ph\u1ea3i nh\u00e2n v\u1edbi 3.) 2. Luy\u1ec7n t\u1eadp B\u00e0i 1: Th\u1ef1c hi\u1ec7n t\u01b0\u01a1ng t\u1ef1 b\u00e0i Th\u1ef1c h\u00e0nh 1. \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. B\u00e0i 2: \u2013 HS th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. a) \u0110 268","b) \u0110 (r\u00fat g\u1ecdn \u0111\u1ec3 c\u00f3 m\u1eabu s\u1ed1 b\u1eb1ng nhau). c) S (m\u1eabu s\u1ed1 kh\u00f4ng gi\u1ed1ng nhau). L\u01b0u \u00fd: Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 c\u00e1c ph\u00e2n s\u1ed1 l\u00e0 l\u00e0m cho c\u00e1c m\u1eabu s\u1ed1 b\u1eb1ng nhau. Do \u0111\u00f3 c\u00f3 th\u1ec3 d\u00f9ng c\u00e1ch r\u00fat g\u1ecdn ph\u00e2n s\u1ed1 (trong tr\u01b0\u1eddng h\u1ee3p thu\u1eadn ti\u1ec7n). B\u00e0i 3: \u2013 HS (nh\u00f3m b\u1ed1n) x\u00e1c \u0111\u1ecbnh y\u00eau c\u1ea7u: Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 hai ph\u00e2n s\u1ed1 \u2192 T\u00ecm hi\u1ec3u m\u1eabu \u2192 T\u00ecm c\u00e1ch l\u00e0m. \u2013 HS l\u00e0m c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. \u2013 S\u1eeda b\u00e0i, HS gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. a) 5 v\u00e0 2 b) 16 v\u00e0 3 c) 1 v\u00e0 15 5 5 8 8 3 3 Ch\u1eb3ng h\u1ea1n: 1 v\u00e0 2 t\u1ee9c l\u00e0 5 v\u00e0 2 5 5 5 M\u1eabu s\u1ed1 chung l\u00e0 5. 1 = 1\u00d7 5 = 55\t 1 1\u00d7 5 IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m Ho\u1ea1t \u0111\u1ed9ng th\u1ef1c t\u1ebf C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c cho c\u00e1c nh\u00f3m th\u1ea3o lu\u1eadn, thi \u0111ua xem nh\u00f3m n\u00e0o nhanh nh\u1ea5t. S\u1eeda b\u00e0i, khuy\u1ebfn kh\u00edch c\u00e1c nh\u00f3m tr\u00ecnh b\u00e0y. Ch\u1eb3ng h\u1ea1n: \u0110\u1ec3 thu\u1eadn l\u1ee3i cho vi\u1ec7c chia \u0111\u1ea5t \u2192 Chia m\u1ea3nh \u0111\u1ea5t th\u00e0nh c\u00e1c ph\u1ea7n b\u1eb1ng nhau sao cho d\u1ec5 d\u00e0ng trong vi\u1ec7c ch\u1ec9 ra ph\u1ea7n \u0111\u1ea5t t\u01b0\u01a1ng \u1ee9ng v\u1edbi c\u00e1c ph\u00e2n s\u1ed1 1 ; 1 ; 1 . 2 3 6 \u2192 C\u1ea7n quy \u0111\u1ed3ng m\u1eabu s\u1ed1 ba ph\u00e2n s\u1ed1 \u2192 M\u1eabu s\u1ed1 chung l\u00e0 6 \u2192 Chia m\u1ea3nh \u0111\u1ea5t th\u00e0nh 6 ph\u1ea7n b\u1eb1ng nhau (kh\u00f4ng c\u1ea7n th\u1ef1c hi\u1ec7n ph\u1ea7n quy \u0111\u1ed3ng). 269","B\u00e0i 66. SO S\u00c1NH HAI PH\u00c2N S\u1ed0 (2 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS nh\u1eadn bi\u1ebft c\u00e1ch so s\u00e1nh hai ph\u00e2n s\u1ed1; th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c vi\u1ec7c so s\u00e1nh hai ph\u00e2n s\u1ed1; x\u00e1c \u0111\u1ecbnh ph\u00e2n s\u1ed1 l\u1edbn nh\u1ea5t v\u00e0 ph\u00e2n s\u1ed1 b\u00e9 nh\u1ea5t; s\u1eafp x\u1ebfp \u0111\u01b0\u1ee3c th\u1ee9 t\u1ef1 c\u00e1c ph\u00e2n s\u1ed1 (trong tr\u01b0\u1eddng h\u1ee3p c\u00e1c ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng m\u1eabu s\u1ed1, c\u00f3 m\u1ed9t m\u1eabu s\u1ed1 chia h\u1ebft cho c\u00e1c m\u1eabu s\u1ed1 c\u00f2n l\u1ea1i). \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft nh\u1eefng v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn vi\u1ec7c so s\u00e1nh ph\u00e2n s\u1ed1. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t nh\u00e2n \u00e1i, tr\u00e1ch nhi\u1ec7m. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh c\u00f3 trong b\u00e0i (n\u1ebfu c\u1ea7n). C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ho\u1ea1t \u0111\u1ed9ng nh\u00f3m \u0111\u00f4i (m\u1ed7i nh\u00f3m th\u1ef1c hi\u1ec7n c\u00f4ng vi\u1ec7c \u1edf m\u1ed9t h\u00ecnh v\u1ebd trong ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng). C\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n theo c\u00e1c y\u00eau c\u1ea7u sau: \u2013 Quan s\u00e1t h\u00ecnh v\u1ebd. \u2013 Vi\u1ebft ph\u00e2n s\u1ed1 ch\u1ec9 ph\u1ea7n b\u00e1nh \u0111\u00e3 \u0103n c\u1ee7a m\u1ed7i b\u1ea1n nh\u1ecf. \u2013 D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd, so s\u00e1nh hai ph\u00e2n s\u1ed1 v\u1eeba vi\u1ebft. \u2013 Th\u00f4ng b\u00e1o k\u1ebft qu\u1ea3 v\u00e0 gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. 1 < 2 (1 mi\u1ebfng \u00edt h\u01a1n 2 mi\u1ebfng) 9 9 1 1 4 > 8 (1 mi\u1ebfng \u1edf c\u00e1i b\u00e1nh th\u1ee9 nh\u1ea5t l\u1edbn h\u01a1n 1 mi\u1ebfng \u1edf c\u00e1i b\u00e1nh th\u1ee9 hai) GV \u0111\u1eb7t v\u1ea5n \u0111\u1ec1: Ta \u0111\u00e3 d\u1ef1a v\u00e0o h\u00ecnh v\u1ebd \u0111\u1ec3 so s\u00e1nh ph\u00e2n s\u1ed1, n\u1ebfu kh\u00f4ng c\u00f3 h\u00ecnh \u1ea3nh th\u00ec ta so s\u00e1nh hai ph\u00e2n s\u1ed1 th\u1ebf n\u00e0o? \u2192 Gi\u1edbi thi\u1ec7u b\u00e0i m\u1edbi. II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: So s\u00e1nh hai ph\u00e2n s\u1ed1 GV g\u1ee3i \u00fd, HS \u0111\u00f3ng g\u00f3p \u00fd ki\u1ebfn x\u00e2y d\u1ef1ng b\u00e0i. GV: Khi so s\u00e1nh hai ph\u00e2n s\u1ed1, \u0111i\u1ec1u \u0111\u1ea7u ti\u00ean ta quan t\u00e2m l\u00e0 m\u1eabu c\u1ee7a hai ph\u00e2n s\u1ed1 \u0111\u00f3 c\u00f3 b\u1eb1ng nhau kh\u00f4ng? C\u00f3 hai kh\u1ea3 n\u0103ng: 1. So s\u00e1nh hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1 1 2 V\u00ed d\u1ee5 1: So s\u00e1nh hai ph\u00e2n s\u1ed1 9 v\u00e0 9 . GV \t\t HS \u2013 Nh\u1eadn x\u00e9t m\u1eabu s\u1ed1 c\u1ee7a hai ph\u00e2n s\u1ed1.\t\t\t Hai ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng m\u1eabu s\u1ed1 l\u00e0 9. \u2013 D\u1ef1a v\u00e0o \u0111\u00e2u \u0111\u1ec3 so s\u00e1nh 2 ph\u00e2n s\u1ed1? \t\t D\u1ef1a v\u00e0o t\u1eed s\u1ed1. 270","\u2013 H\u00e3y so s\u00e1nh 1 v\u00e0 2 .\t\t\t\t\t 1 < 2 . 9 9 9 9 \u2013 Gi\u1ea3i th\u00edch?\t\t\t\t\t\t Do 1 < 2. h91ai<ph29\u00e2. n \u2013 GV vi\u1ebft b\u1ea3ng: s\u1ed1 c\u00f3 c\u00f9ng m\u1eabu s\u1ed1 \u2013 Mu\u1ed1n so s\u00e1nh ta l\u00e0m th\u1ebf n\u00e0o? \t\t\t\t\t\t So s\u00e1nh hai t\u1eed s\u1ed1. \u2013 GV \u0111\u1ecdc quy t\u1eafc trong SGK. 2. So s\u00e1nh hai ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1 V\u00ed d\u1ee5 2: So s\u00e1nh hai ph\u00e2n s\u1ed1 1 v\u00e0 1 . 4 8 GV \t\t HS \u2013 Nh\u1eadn x\u00e9t m\u1eabu s\u1ed1 c\u1ee7a hai ph\u00e2n s\u1ed1. \t Hai ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1. \t \u2013 L\u00e0m sao \u0111\u1ec3 so s\u00e1nh hai ph\u00e2n s\u1ed1 n\u00e0y? \t Th\u1ea3o lu\u1eadn \u2192 Quy \u0111\u1ed3ng m\u1eabu s\u1ed1. \u2013 H\u00e3y quy \u0111\u1ed3ng m\u1eabu s\u1ed1 hai ph\u00e2n s\u1ed1 n\u00e0y. \t HS th\u1ef1c hi\u1ec7n (b\u1ea3ng con), tr\u00ecnh b\u00e0y. \u2013 GV vi\u1ebft b\u1ea3ng. 1 = 1\u00d7 2 = 2 ; 2 > 1 . 4 4\u00d7 2 8 8 8 1 1 V\u1eady 4 > 8 . \u2013 Mu\u1ed1n so s\u00e1nh hai ph\u00e2n s\u1ed1 c\u00f3 kh\u00e1c m\u1eabu s\u1ed1 ta l\u00e0m th\u1ebf n\u00e0o? \u2013 Quy \u0111\u1ed3ng m\u1eabu s\u1ed1. \u2013 GV \u0111\u1ecdc quy t\u1eafc trong SGK. III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 HS \u0111\u1ecdc y\u00eau c\u1ea7u. \u2013 GV l\u01b0u \u00fd HS m\u1ed9t s\u1ed1 \u0111i\u1ec1u khi th\u1ef1c hi\u1ec7n b\u00e0i so s\u00e1nh ph\u00e2n s\u1ed1. \u2022 Quan s\u00e1t hai m\u1eabu s\u1ed1. N\u1ebfu m\u1eabu s\u1ed1 b\u1eb1ng nhau \u2192 D\u1ef1a v\u00e0o t\u1eed s\u1ed1 so s\u00e1nh ngay hai ph\u00e2n s\u1ed1. N\u1ebfu m\u1eabu s\u1ed1 kh\u00e1c nhau \u2192 Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 \u2192 So s\u00e1nh hai ph\u00e2n s\u1ed1. \u2022 N\u1ebfu y\u00eau c\u1ea7u c\u1ee7a b\u00e0i l\u00e0 So s\u00e1nh hai ph\u00e2n s\u1ed1: Tr\u00ecnh b\u00e0y theo m\u1eabu \u1edf ph\u1ea7n b\u00e0i m\u1edbi. \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n. L\u01b0u \u00fd: C\u00e2u b), \u00fd cu\u1ed1i c\u00f3 th\u1ec3 l\u00e0m b\u1eb1ng c\u00e1ch r\u00fat g\u1ecdn. 2. Luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS \u0111\u1ecdc y\u00eau c\u1ea7u, th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n r\u1ed3i chia s\u1ebb nh\u00f3m b\u1ed1n. \u2013 S\u1eeda b\u00e0i: T\u1ed5 ch\u1ee9c cho c\u00e1c nh\u00f3m thi \u0111ua. \u2013 GV l\u01b0u \u00fd HS m\u1ed9t s\u1ed1 \u0111i\u1ec1u khi th\u1ef1c hi\u1ec7n b\u00e0i s\u1eafp x\u1ebfp c\u00e1c ph\u00e2n s\u1ed1 theo th\u1ee9 t\u1ef1. 271","\u2022 Quan s\u00e1t c\u00e1c m\u1eabu s\u1ed1. N\u1ebfu c\u00e1c m\u1eabu s\u1ed1 b\u1eb1ng nhau \u2192 D\u1ef1a v\u00e0o t\u1eed s\u1ed1 so s\u00e1nh ngay c\u00e1c ph\u00e2n s\u1ed1 r\u1ed3i s\u1eafp x\u1ebfp th\u1ee9 t\u1ef1. N\u1ebfu m\u1eabu s\u1ed1 kh\u00e1c nhau: \u2192 Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 \u2192 \u0110\u1ecbnh v\u1ecb tr\u00ed c\u00e1c ph\u00e2n s\u1ed1 s\u1ebd s\u1eafp x\u1ebfp, ch\u1eb3ng h\u1ea1n: \u2026\u2026 ; \u2026\u2026 ; \u2026\u2026 ; \u2026\u2026 \u2192 X\u00e1c \u0111\u1ecbnh ph\u00e2n s\u1ed1 l\u1edbn nh\u1ea5t, ph\u00e2n s\u1ed1 b\u00e9 nh\u1ea5t, vi\u1ebft v\u00e0o v\u1ecb tr\u00ed \u0111\u00e3 \u0111\u1ecbnh (\u1edf tr\u00ean). \u2192 So s\u00e1nh hai ph\u00e2n s\u1ed1 c\u00f2n l\u1ea1i, vi\u1ebft v\u00e0o v\u1ecb tr\u00ed theo th\u1ee9 t\u1ef1 b\u00e0i y\u00eau c\u1ea7u. \u2022 N\u1ebfu y\u00eau c\u1ea7u c\u1ee7a b\u00e0i l\u00e0 S\u1eafp x\u1ebfp c\u00e1c ph\u00e2n s\u1ed1 theo th\u1ee9 t\u1ef1 hay T\u00ecm ph\u00e2n s\u1ed1 l\u1edbn nh\u1ea5t, ph\u00e2n s\u1ed1 b\u00e9 nh\u1ea5t: B\u01b0\u1edbc quy \u0111\u1ed3ng m\u1eabu s\u1ed1 ch\u1ec9 c\u1ea7n ghi k\u1ebft qu\u1ea3 c\u1ee7a vi\u1ec7c quy \u0111\u1ed3ng, kh\u00f4ng c\u1ea7n tr\u00ecnh b\u00e0y c\u1ee5 th\u1ec3 vi\u1ec7c quy \u0111\u1ed3ng. Ch\u1eb3ng h\u1ea1n: a) 1 ; 3 ; 5 2 4 8 4 ; 6 ; 5 8 8 8 6 ; 5 ; 4 (b\u01b0\u1edbc n\u00e0y kh\u00f4ng nh\u1ea5t thi\u1ebft ph\u1ea3i vi\u1ebft) 8 8 8 V\u1eady: 3 ; 5 ; 1 . 4 8 2 B\u00e0i 2: \u2013 HS \u0111\u1ecdc y\u00eau c\u1ea7u r\u1ed3i th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, khuy\u1ebfn kh\u00edch HS gi\u1ea3i th\u00edch. a) Ph\u1ea7n b\u00e1nh Thu \u0103n b\u1eb1ng 1 c\u00e1i b\u00e1nh. Ph\u1ea7n b\u00e1nh V\u00e2n \u0103n \u00edt h\u01a1n 1 c\u00e1i b\u00e1nh. Ph\u1ea7n b\u00e1nh Khang \u0103n nhi\u1ec1u h\u01a1n 1 c\u00e1i b\u00e1nh. b) 4 = 1 (d\u1ef1a v\u00e0o h\u00ecnh \u1ea3nh ho\u1eb7c quy \u0111\u1ed3ng m\u1eabu s\u1ed1) 4 3 < 1 4 5 4 > 1 c) N\u1ebfu t\u1eed s\u1ed1 b\u1eb1ng m\u1eabu s\u1ed1 th\u00ec ph\u00e2n s\u1ed1 b\u1eb1ng 1. N\u1ebfu t\u1eed s\u1ed1 b\u00e9 h\u01a1n m\u1eabu s\u1ed1 th\u00ec ph\u00e2n s\u1ed1 b\u00e9 h\u01a1n 1. N\u1ebfu t\u1eed s\u1ed1 l\u1edbn h\u01a1n m\u1eabu s\u1ed1 th\u00ec ph\u00e2n s\u1ed1 l\u1edbn h\u01a1n 1. B\u00e0i 3: \u2013 HS \u0111\u1ecdc y\u00eau c\u1ea7u r\u1ed3i th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, khuy\u1ebfn kh\u00edch HS gi\u1ea3i th\u00edch. a) 7 \t\t\t b) 9 \t\t\tc) 7 7 7 9 272","IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 4: \u2013 HS \u0111\u1ecdc y\u00eau c\u1ea7u r\u1ed3i th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n. \u2013 S\u1eeda b\u00e0i, khuy\u1ebfn kh\u00edch HS gi\u1ea3i th\u00edch. Do 4 gi\u1edd > 1 gi\u1edd; 1 gi\u1edd > 3 gi\u1edd n\u00ean: 3 4 a) Th\u1eddi gian \u0111\u1ecdc s\u00e1ch \u1edf th\u01b0 vi\u1ec7n c\u1ee7a Ph\u01b0\u01a1ng nhi\u1ec1u nh\u1ea5t. b) Th\u1eddi gian \u0111\u1ecdc s\u00e1ch \u1edf th\u01b0 vi\u1ec7n c\u1ee7a Th\u00e0nh \u00edt nh\u1ea5t. Ho\u1ea1t \u0111\u1ed9ng th\u1ef1c t\u1ebf B\u00e0i n\u00e0y gi\u00fap HS nh\u1eadn bi\u1ebft c\u00f3 th\u1ec3 so s\u00e1nh tr\u1ef1c ti\u1ebfp hai ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng t\u1eed s\u1ed1. T\u1ed5 ch\u1ee9c tr\u00f2 ch\u01a1i \u0111\u1ec3 c\u00e1c nh\u00f3m tham gia. S\u1eeda b\u00e0i. 5 6 \u2022 Ph\u00e2n s\u1ed1 ch\u1ec9 ph\u1ea7n t\u00f4 m\u00e0u c\u1ee7a h\u00ecnh 1 l\u00e0 . Ph\u00e2n s\u1ed1 ch\u1ec9 ph\u1ea7n t\u00f4 m\u00e0u c\u1ee7a h\u00ecnh 2 l\u00e0 5 . 24 \u2022 Do hai h\u00ecnh ch\u1eef nh\u1eadt b\u1eb1ng nhau n\u00ean 5 \u00f4 t\u00f4 m\u00e0u c\u1ee7a h\u00ecnh 1 l\u1edbn h\u01a1n 5 \u00f4 t\u00f4 m\u00e0u c\u1ee7a h\u00ecnh 2. 5 > 5 6 24 \u2022 Trong hai ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng t\u1eed s\u1ed1, ph\u00e2n s\u1ed1 n\u00e0o c\u00f3 m\u1eabu s\u1ed1 b\u00e9 h\u01a1n th\u00ec ph\u00e2n s\u1ed1 \u0111\u00f3 l\u1edbn h\u01a1n. B\u00e0i 67. EM L\u00c0M \u0110\u01af\u1ee2C NH\u1eeeNG G\u00cc? (2 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c vi\u1ec7c r\u00fat g\u1ecdn, quy \u0111\u1ed3ng, so s\u00e1nh ph\u00e2n s\u1ed1. \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn c\u00e1c ki\u1ebfn th\u1ee9c v\u1ec1 ph\u00e2n s\u1ed1 \u0111\u00e3 h\u1ecdc. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t tr\u00e1ch nhi\u1ec7m, nh\u00e2n \u00e1i. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: B\u1ea3ng b\u00e0i 6 (n\u1ebfu c\u1ea7n). C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ch\u01a1i tr\u00f2 ch\u01a1i \u201cT\u00f4i b\u1ea3o\u201d. \u2013 GV: T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? 273","\u2013 GV: T\u00f4i b\u1ea3o c\u00e1c b\u1ea1n T\u1ed5 1 vi\u1ebft m\u1ed9t ph\u00e2n s\u1ed1 l\u1edbn h\u01a1n 1, c\u00e1c b\u1ea1n T\u1ed5 2 vi\u1ebft m\u1ed9t ph\u00e2n s\u1ed1 b\u00e9 h\u01a1n 1, c\u00e1c b\u1ea1n c\u00f2n l\u1ea1i vi\u1ebft m\u1ed9t ph\u00e2n s\u1ed1 b\u1eb1ng 1. \u2013 HS vi\u1ebft tr\u00ean b\u1ea3ng con. \u2013 GV l\u1ea5y m\u1ed9t v\u00e0i b\u1ea3ng con l\u00e0m m\u1eabu, HS gi\u1ea3i th\u00edch (d\u1ef1a v\u00e0o quan h\u1ec7 gi\u1eefa t\u1eed s\u1ed1 v\u00e0 m\u1eabu s\u1ed1). II. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 Khi s\u1eeda b\u00e0i, khuy\u1ebfn kh\u00edch nhi\u1ec1u HS tr\u00ecnh b\u00e0y b\u00e0i l\u00e0m c\u1ee7a m\u00ecnh. B\u00e0i 2: \u2013 HS nh\u1eadn bi\u1ebft y\u00eau c\u1ea7u. GV gi\u00fap c\u00e1c em nh\u1eafc l\u1ea1i nh\u1eefng l\u01b0u \u00fd khi l\u00e0m b\u00e0i r\u00fat g\u1ecdn ph\u00e2n s\u1ed1. \u2022 Khi t\u00ecm c\u00e1c s\u1ed1 \u0111\u1ec3 r\u00fat g\u1ecdn, ng\u01b0\u1eddi ta th\u01b0\u1eddng \u0111\u1ec3 \u00fd c\u00e1c tr\u01b0\u1eddng h\u1ee3p \u0111\u1eb7c bi\u1ec7t: S\u1ed1 chia h\u1ebft cho 2 (s\u1ed1 ch\u1eb5n). S\u1ed1 chia h\u1ebft cho 5 (s\u1ed1 c\u00f3 t\u1eadn c\u00f9ng l\u00e0 0 ho\u1eb7c 5). S\u1ed1 chia h\u1ebft cho 10 (s\u1ed1 c\u00f3 t\u1eadn c\u00f9ng l\u00e0 0). C\u00e1c tr\u01b0\u1eddng h\u1ee3p chia h\u1ebft cho 3, 4, 6, 7, 8, 9: V\u1eadn d\u1ee5ng b\u1ea3ng nh\u00e2n, b\u1ea3ng chia. \u2022 C\u00e1ch tr\u00ecnh b\u00e0y. \u2022 K\u1ebft qu\u1ea3 ph\u1ea3i l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, l\u01b0u \u00fd c\u00e1c em th\u01b0\u1eddng xuy\u00ean ki\u1ec3m tra l\u1ea1i. B\u00e0i 3: \u2013 HS nh\u1eadn bi\u1ebft y\u00eau c\u1ea7u, th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. \u2013 GV gi\u00fap c\u00e1c em nh\u1edb nh\u1eefng l\u01b0u \u00fd khi l\u00e0m b\u00e0i quy \u0111\u1ed3ng m\u1eabu s\u1ed1 c\u00e1c ph\u00e2n s\u1ed1. \u2022 N\u00ean r\u00fat g\u1ecdn c\u00e1c ph\u00e2n s\u1ed1 ch\u01b0a t\u1ed1i gi\u1ea3n \u0111\u1ec3 vi\u1ec7c t\u00ecm m\u1eabu s\u1ed1 chung d\u1ec5 d\u00e0ng h\u01a1n. \u2022 Ch\u1ecdn m\u1eabu s\u1ed1 chung l\u00e0 m\u1eabu s\u1ed1 l\u1edbn h\u01a1n. \u2022 T\u00ecm xem m\u1eabu s\u1ed1 chung g\u1ea5p m\u1ea5y l\u1ea7n c\u00e1c m\u1eabu s\u1ed1 c\u00f2n l\u1ea1i, t\u1eeb \u0111\u00f3 s\u1ebd x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c c\u00e1c t\u1eed s\u1ed1 ph\u1ea3i nh\u00e2n v\u1edbi m\u1ea5y. \u2022 L\u01b0u \u00fd c\u00e1ch tr\u00ecnh b\u00e0y. Ch\u1eb3ng h\u1ea1n: a) 5 v\u00e0 28 b) 2 v\u00e0 17 c) 9 v\u00e0 5 3 12 9 81 24 8 28 = 28 : 4 = 7 \t 2 = 2\u00d79 = 18 9 = 9:3 = 3 12 12 : 4 3 9 9\u00d79 81 24 24 : 3 8 V\u1eady 5 v\u00e0 7 . V\u1eady 18 v\u00e0 8117 . V\u1eady 3 v\u00e0 5 . 3 3 81 8 8 B\u00e0i 4: \u2013 HS nh\u1eadn bi\u1ebft y\u00eau c\u1ea7u, th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. \u2013 GV gi\u00fap c\u00e1c em nh\u1edb nh\u1eefng l\u01b0u \u00fd khi l\u00e0m b\u00e0i s\u1eafp x\u1ebfp c\u00e1c ph\u00e2n s\u1ed1 theo th\u1ee9 t\u1ef1. 274","\u2022 Quan s\u00e1t c\u00e1c m\u1eabu s\u1ed1. N\u1ebfu c\u00e1c m\u1eabu s\u1ed1 b\u1eb1ng nhau \u2192 D\u1ef1a v\u00e0o t\u1eed s\u1ed1 so s\u00e1nh ngay c\u00e1c ph\u00e2n s\u1ed1 r\u1ed3i x\u1ebfp th\u1ee9 t\u1ef1. N\u1ebfu m\u1eabu s\u1ed1 kh\u00e1c nhau \u2192 Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 \u2192 \u0110\u1ecbnh v\u1ecb tr\u00ed c\u00e1c ph\u00e2n s\u1ed1 s\u1ebd s\u1eafp x\u1ebfp, ch\u1eb3ng h\u1ea1n: \u2026\u2026 ; \u2026\u2026 ; \u2026\u2026 ; \u2026\u2026 \u2192 X\u00e1c \u0111\u1ecbnh ph\u00e2n s\u1ed1 l\u1edbn nh\u1ea5t, ph\u00e2n s\u1ed1 b\u00e9 nh\u1ea5t, vi\u1ebft v\u00e0o v\u1ecb tr\u00ed \u0111\u00e3 \u0111\u1ecbnh (\u1edf tr\u00ean) \u2192 So s\u00e1nh hai ph\u00e2n s\u1ed1 c\u00f2n l\u1ea1i, vi\u1ebft v\u00e0o v\u1ecb tr\u00ed theo th\u1ee9 t\u1ef1 b\u00e0i y\u00eau c\u1ea7u. N\u1ebfu y\u00eau c\u1ea7u c\u1ee7a b\u00e0i l\u00e0 S\u1eafp x\u1ebfp c\u00e1c ph\u00e2n s\u1ed1 theo th\u1ee9 t\u1ef1 hay T\u00ecm ph\u00e2n s\u1ed1 l\u1edbn nh\u1ea5t, ph\u00e2n s\u1ed1 b\u00e9 nh\u1ea5t: B\u01b0\u1edbc quy \u0111\u1ed3ng m\u1eabu s\u1ed1 ch\u1ec9 c\u1ea7n ghi k\u1ebft qu\u1ea3 c\u1ee7a vi\u1ec7c quy \u0111\u1ed3ng, kh\u00f4ng c\u1ea7n tr\u00ecnh b\u00e0y c\u1ee5 th\u1ec3 vi\u1ec7c quy \u0111\u1ed3ng. a) 2 ; 1 ; 11 ; 5 3 2 18 9 12 ; 9 ; 11 ; 10 18 18 18 18 9 ; 10 ; 11 ; 12 18 18 18 18 V\u1eady 1 ; 5 ; 11 ; 2 . 2 9 18 3 b) 5 ; 1 ; 1 3 3 5 1 3 > 1 v\u00e0 3 <1 V\u1eady 1 ; 1; 5 (s\u1eed d\u1ee5ng vi\u1ec7c so s\u00e1nh ph\u00e2n s\u1ed1 v\u1edbi 1). 3 3 B\u00e0i 5: \u2013 HS nh\u1eadn bi\u1ebft y\u00eau c\u1ea7u, th\u1ef1c hi\u1ec7n nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, HS tr\u00ecnh b\u00e0y c\u00e1ch l\u00e0m. 5 > .?. 8 4 \u2022 Th\u1eed v\u1edbi .?. = 4. X\u00e9t 5 v\u00e0 4 (= 8 ) \u2192 lo\u1ea1i. 8 4 8 \u2022 Th\u1eed v\u1edbi .?. = 3. X\u00e9t 5 v\u00e0 3 (= 6 ) \u2192 lo\u1ea1i. 8 4 8 \u2022 Th\u1eed v\u1edbi .?. = 2. X\u00e9t 5 v\u00e0 2 (= 4 ) \u2192 ch\u1ecdn. 8 4 8 \u2192 Ch\u1ecdn C (2). 275","III. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 6: \u2013 HS nh\u1eadn bi\u1ebft y\u00eau c\u1ea7u, th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. \u2013 S\u1eeda b\u00e0i, HS tr\u00ecnh b\u00e0y c\u00e1ch l\u00e0m. \u2022 6 :8 = 6 = 3 (qu\u1ea3 cam) \u2022 8 = 8 4 8 1 (qu\u1ea3 cam) \u2013 GV h\u1ec7 th\u1ed1ng c\u00e1ch l\u00e0m. S\u1ed1 qu\u1ea3 cam : S\u1ed1 b\u1ea1n = Ph\u1ea7n cam m\u1ed7i b\u1ea1n \u0111\u01b0\u1ee3c chia \u2192 Chuy\u1ec3n ph\u00e9p chia v\u1ec1 d\u1ea1ng ph\u00e2n s\u1ed1 \u2192 R\u00fat g\u1ecdn. B\u00e0i 7: \u2013 HS nh\u1eadn bi\u1ebft y\u00eau c\u1ea7u, th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. \u2013 S\u1eeda b\u00e0i, HS tr\u00ecnh b\u00e0y c\u00e1ch l\u00e0m. a) \u0110 (v\u00ec 5 < 1). 8 8 8 8 b) S ( 8 < 5 v\u00ec 5 > 1). \u0110\u1ea5t n\u01b0\u1edbc em Ho\u1ea1t \u0111\u1ed9ng nh\u00f3m. C\u00e1c nh\u00f3m nh\u1eadn bi\u1ebft nh\u1eefng th\u00f4ng tin c\u1ea7n thi\u1ebft: 96 huy ch\u01b0\u01a1ng v\u00e0ng, 92 huy ch\u01b0\u01a1ng b\u1ea1c, 100 huy ch\u01b0\u01a1ng \u0111\u1ed3ng. C\u1ea7n vi\u1ebft ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n ch\u1ec9 s\u1ed1 huy ch\u01b0\u01a1ng v\u00e0ng so v\u1edbi t\u1ed5ng s\u1ed1 huy ch\u01b0\u01a1ng \u2192 T\u00ednh t\u1ed5ng s\u1ed1 huy ch\u01b0\u01a1ng (96 + 92 + 100 = 288) 96 \u2192 Vi\u1ebft ph\u00e2n s\u1ed1 288 \u2192 Nh\u1eadn x\u00e9t: N\u1ebfu l\u1ea5y 4 huy ch\u01b0\u01a1ng \u0111\u1ed3ng chuy\u1ec3n qua huy ch\u01b0\u01a1ng b\u1ea1c th\u00ec m\u1ed7i lo\u1ea1i \u0111\u1ec1u c\u00f3 96 huy ch\u01b0\u01a1ng. Nh\u01b0 v\u1eady 96 l\u00e0 trung b\u00ecnh c\u1ed9ng c\u1ee7a 96, 92 v\u00e0 98 Hay 96 \u00d7 3 = 288 \u2192 R\u00fat g\u1ecdn: 96 = 96 : 96 = 1 288 288 : 96 3 1 \u2192 K\u1ebft lu\u1eadn: S\u1ed1 huy ch\u01b0\u01a1ng v\u00e0ng trong t\u1ed5ng s\u1ed1 huy ch\u01b0\u01a1ng l\u00e0 3 . L\u01b0u \u00fd: HS c\u0169ng c\u00f3 th\u1ec3 l\u00e0m nh\u01b0 sau: \u2192 T\u00ednh t\u1ed5ng s\u1ed1 huy ch\u01b0\u01a1ng (96 + 92 + 100 = 288) \u2192 Vi\u1ebft ph\u00e2n s\u1ed1 96 288 276","\u2192 Nh\u1eadn x\u00e9t: N\u1ebfu l\u1ea5y 288 : 96 = 3 \u2192 T\u1ed5ng s\u1ed1 huy ch\u01b0\u01a1ng g\u1ea5p 3 l\u1ea7n s\u1ed1 huy ch\u01b0\u01a1ng v\u00e0ng. \u2192 R\u00fat g\u1ecdn: 96 = 96 : 96 = 1 288 288 : 96 3 1 \u2192 K\u1ebft lu\u1eadn: S\u1ed1 huy ch\u01b0\u01a1ng v\u00e0ng trong t\u1ed5ng s\u1ed1 huy ch\u01b0\u01a1ng l\u00e0 3 . B\u00e0i 68. C\u1ed8NG HAI PH\u00c2N S\u1ed0 C\u00d9NG M\u1eaaU S\u1ed0 (1 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS nh\u1eadn bi\u1ebft \u0111\u01b0\u1ee3c c\u00e1ch c\u1ed9ng ph\u00e2n s\u1ed1, th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c ph\u00e9p c\u1ed9ng ph\u00e2n s\u1ed1 trong tr\u01b0\u1eddng h\u1ee3p c\u00e1c ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng m\u1eabu s\u1ed1. \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn ph\u00e9p c\u1ed9ng ph\u00e2n s\u1ed1, m\u1edf r\u1ed9ng c\u00e1c t\u00ednh ch\u1ea5t c\u1ee7a ph\u00e9p c\u1ed9ng c\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean sang ph\u00e9p c\u1ed9ng ph\u00e2n s\u1ed1. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t nh\u00e2n \u00e1i, tr\u00e1ch nhi\u1ec7m. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh c\u00f3 trong b\u00e0i (n\u1ebfu c\u1ea7n). HS: Gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng d\u00f9ng cho ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng. C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ho\u1ea1t \u0111\u1ed9ng nh\u00f3m. C\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n theo c\u00e1c y\u00eau c\u1ea7u sau: \u2013 Quan s\u00e1t h\u00ecnh v\u1ebd. \u2013 Vi\u1ebft ph\u00e9p t\u00ednh bi\u1ec3u th\u1ecb t\u1ed5ng s\u1ed1 ph\u1ea7n c\u1ee7a t\u1edd gi\u1ea5y \u0111\u00e3 \u0111\u01b0\u1ee3c t\u00f4 m\u00e0u. \u2013 D\u00f9ng gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng, th\u1ef1c hi\u1ec7n vi\u1ec7c t\u00ednh t\u1ed5ng. \u2013 Th\u00f4ng b\u00e1o k\u1ebft qu\u1ea3 v\u00e0 gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. GV \u0111\u01b0a h\u00ecnh \u1ea3nh l\u00ean b\u1ea3ng. Chia t\u1edd gi\u1ea5y th\u00e0nh 8 ph\u1ea7n b\u1eb1ng nhau. 3 1 T\u00f4 m\u00e0u \u0111\u1ecf 8 t\u1edd gi\u1ea5y v\u00e0 t\u00f4 m\u00e0u xanh 8 t\u1edd gi\u1ea5y. 277","D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd: T\u1ed5ng s\u1ed1 ph\u1ea7n c\u1ee7a t\u1edd gi\u1ea5y \u0111\u00e3 \u0111\u01b0\u1ee3c t\u00f4 m\u00e0u l\u00e0 4 hay 1 t\u1edd gi\u1ea5y. V\u1eady 8 2 3 + 1 = 1 . 8 8 2 GV \u0111\u1eb7t v\u1ea5n \u0111\u1ec1: Ta \u0111\u00e3 d\u1ef1a v\u00e0o h\u00ecnh v\u1ebd \u0111\u1ec3 t\u00ednh t\u1ed5ng c\u00e1c ph\u00e2n s\u1ed1, n\u1ebfu kh\u00f4ng c\u00f3 h\u00ecnh \u1ea3nh th\u00ec ta c\u1ed9ng hai ph\u00e2n s\u1ed1 th\u1ebf n\u00e0o? \u2192 Gi\u1edbi thi\u1ec7u b\u00e0i m\u1edbi. II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: C\u1ed9ng hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1 GV g\u1ee3i \u00fd, HS \u0111\u00f3ng g\u00f3p \u00fd ki\u1ebfn x\u00e2y d\u1ef1ng b\u00e0i. V\u00ed d\u1ee5: 3 + 1 . 8 8 GV \t\t HS \u2013 Nh\u1eadn x\u00e9t m\u1eabu s\u1ed1 c\u1ee7a hai ph\u00e2n s\u1ed1. \t Hai ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng m\u1eabu s\u1ed1 l\u00e0 8. \u2013 Ta c\u1ed9ng th\u1ebf n\u00e0o? (Ch\u1ec9 tay v\u00e0o h\u00ecnh.) \t L\u1ea5y 3 c\u1ed9ng v\u1edbi 1. 3 1 8 t\u1edd gi\u1ea5y c\u1ed9ng 8 t\u1edd gi\u1ea5y, t\u1ee9c l\u00e0 t\u1ed5ng c\u1ee7a 3 v\u00e0 1 (ph\u1ea7n 8) t\u1edd gi\u1ea5y. Ta vi\u1ebft 3 + 1 = 4 = 1 . 8 8 2 K\u1ebft qu\u1ea3 ph\u00e9p t\u00ednh l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. \t So s\u00e1nh v\u1edbi k\u1ebft qu\u1ea3 \u1edf ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng. \u2013 Mu\u1ed1n c\u1ed9ng hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1, \t L\u1ea5y t\u1eed s\u1ed1 c\u1ed9ng t\u1eed s\u1ed1, m\u1eabu s\u1ed1 l\u00e0 ta l\u00e0m th\u1ebf n\u00e0o? \t m\u1eabu s\u1ed1 chung. \u2013 GV \u0111\u1ecdc quy t\u1eafc trong SGK. III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. C\u00f3 th\u1ec3 tr\u00ecnh b\u00e0y h\u00e0ng ngang nh\u01b0 SGK hay xu\u1ed1ng d\u00f2ng. \t 1 + 3 = 1+3 \t hay 1 + 3 10 10 10 10 10 4 1+3 \t = 10 \t = 10 \t = 2 \t\t = 4 5 10 2 \t\t = 5 278","2. Luy\u1ec7n t\u1eadp Tr\u01b0\u1edbc khi luy\u1ec7n t\u1eadp, GV l\u01b0u \u00fd HS khi th\u1ef1c hi\u1ec7n ph\u00e9p c\u1ed9ng hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1. \u2013 C\u1ed9ng t\u1eed s\u1ed1 v\u1edbi t\u1eed s\u1ed1, d\u01b0\u1edbi v\u1ea1ch ngang ch\u1ec9 vi\u1ebft m\u1ed9t m\u1eabu s\u1ed1 chung. \u2013 K\u1ebft qu\u1ea3 cu\u1ed1i c\u00f9ng l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. GV l\u01b0u \u00fd HS khi vi\u1ebft s\u1ed1 t\u1ef1 nhi\u00ean d\u01b0\u1edbi d\u1ea1ng ph\u00e2n s\u1ed1, n\u00ean vi\u1ebft ngay \u0111\u1ec3 hai ph\u00e2n s\u1ed1 c\u00f3 m\u1eabu s\u1ed1 gi\u1ed1ng nhau. Ch\u1eb3ng h\u1ea1n: 2 \t\t\t\t 5 +2 Vi\u1ebft 2 th\u00e0nh ph\u00e2n s\u1ed1 c\u00f3 m\u1eabu s\u1ed1 l\u00e0 5. Nh\u1ea9m: M\u1ea5y chia 5 b\u1eb1ng 2? (10) 10 2 5 \t\t\t 5 + C\u00e1c em c\u00f2n h\u1ea1n ch\u1ebf c\u00f3 th\u1ec3 vi\u1ebft th\u00e0nh ph\u00e2n s\u1ed1 c\u00f3 m\u1eabu s\u1ed1 l\u00e0 1 r\u1ed3i quy \u0111\u1ed3ng m\u1eabu s\u1ed1. IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 2: \u2013 HS ho\u1ea1t \u0111\u1ed9ng nh\u00f3m. \u2013 GV l\u01b0u \u00fd HS: \u2022 Th\u1ee9 t\u1ef1 th\u1ef1c hi\u1ec7n ph\u00e9p t\u00ednh v\u1edbi c\u00e1c ph\u00e2n s\u1ed1 gi\u1ed1ng nh\u01b0 th\u1ee9 t\u1ef1 th\u1ef1c hi\u1ec7n ph\u00e9p t\u00ednh v\u1edbi c\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean. \u2022 B\u00e0i n\u00e0y n\u00ean khuy\u1ebfn kh\u00edch c\u00e1c em t\u00ednh nh\u1ea9m. \u2013 Sau khi s\u1eeda b\u00e0i, GV gi\u00fap HS nh\u1eadn x\u00e9t (nh\u01b0 SGK). B\u00e0i 69. C\u1ed8NG HAI PH\u00c2N S\u1ed0 KH\u00c1C M\u1eaaU S\u1ed0 (1 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c ph\u00e9p c\u1ed9ng ph\u00e2n s\u1ed1 trong tr\u01b0\u1eddng h\u1ee3p c\u00f3 m\u1ed9t m\u1eabu s\u1ed1 chia h\u1ebft cho c\u00e1c m\u1eabu s\u1ed1 c\u00f2n l\u1ea1i. \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn ph\u00e9p c\u1ed9ng ph\u00e2n s\u1ed1, m\u1edf r\u1ed9ng c\u00e1c t\u00ednh ch\u1ea5t c\u1ee7a ph\u00e9p c\u1ed9ng c\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean sang ph\u00e9p c\u1ed9ng ph\u00e2n s\u1ed1. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t nh\u00e2n \u00e1i, tr\u00e1ch nhi\u1ec7m. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh c\u00f3 trong b\u00e0i (n\u1ebfu c\u1ea7n). HS: Gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng d\u00f9ng cho ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng. 279","C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ho\u1ea1t \u0111\u1ed9ng nh\u00f3m. C\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n theo c\u00e1c y\u00eau c\u1ea7u sau: \u2013 Quan s\u00e1t h\u00ecnh v\u1ebd. \u2013 Vi\u1ebft ph\u00e9p t\u00ednh bi\u1ec3u th\u1ecb t\u1ed5ng s\u1ed1 ph\u1ea7n c\u1ee7a t\u1edd gi\u1ea5y \u0111\u00e3 \u0111\u01b0\u1ee3c t\u00f4 m\u00e0u. \u2013 D\u00f9ng gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng, th\u1ef1c hi\u1ec7n vi\u1ec7c t\u00ednh t\u1ed5ng. \u2013 Th\u00f4ng b\u00e1o k\u1ebft qu\u1ea3 v\u00e0 gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. GV \u0111\u01b0a h\u00ecnh \u1ea3nh l\u00ean b\u1ea3ng. Chia t\u1edd gi\u1ea5y th\u00e0nh 4 ph\u1ea7n b\u1eb1ng nhau. T\u00f4 m\u00e0u \u0111\u1ecf 1 t\u1edd gi\u1ea5y v\u00e0 t\u00f4 m\u00e0u xanh 1 t\u1edd gi\u1ea5y. 2 4 D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd: 3 4 T\u1ed5ng s\u1ed1 ph\u1ea7n c\u1ee7a t\u1edd gi\u1ea5y \u0111\u00e3 \u0111\u01b0\u1ee3c t\u00f4 m\u00e0u l\u00e0 t\u1edd gi\u1ea5y. V\u1eady 1 + 1 = 3 . 2 4 4 GV \u0111\u1eb7t v\u1ea5n \u0111\u1ec1: Ta \u0111\u00e3 d\u1ef1a v\u00e0o h\u00ecnh v\u1ebd \u0111\u1ec3 t\u00ednh t\u1ed5ng c\u00e1c ph\u00e2n s\u1ed1, n\u1ebfu kh\u00f4ng c\u00f3 h\u00ecnh \u1ea3nh th\u00ec ta c\u1ed9ng hai ph\u00e2n s\u1ed1 th\u1ebf n\u00e0o? \u2192 Gi\u1edbi thi\u1ec7u b\u00e0i m\u1edbi. II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: C\u1ed9ng hai ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1 GV g\u1ee3i \u00fd, HS \u0111\u00f3ng g\u00f3p \u00fd ki\u1ebfn x\u00e2y d\u1ef1ng b\u00e0i. V\u00ed d\u1ee5: 1 + 1 . 2 4 GV HS \u2013 Nh\u1eadn x\u00e9t m\u1eabu s\u1ed1 c\u1ee7a hai ph\u00e2n s\u1ed1. Hai ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1. \u2013 Ta \u0111\u00e3 chia t\u1edd gi\u1ea5y th\u00e0nh m\u1ea5y ph\u1ea7n 4 ph\u1ea7n. b\u1eb1ng nhau? HS \u0111\u1ecdc k\u1ebft qu\u1ea3 quy \u0111\u1ed3ng. \u2013 T\u1ee9c l\u00e0 ta \u0111\u00e3 quy \u0111\u1ed3ng m\u1eabu s\u1ed1. L\u1ea5y 2 c\u1ed9ng v\u1edbi 1. 2 1 HS \u0111\u1ecdc. = 4 + 4 So s\u00e1nh v\u1edbi k\u1ebft qu\u1ea3 \u1edf ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng. \u2013 Ta c\u1ed9ng th\u1ebf n\u00e0o? Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 r\u1ed3i c\u1ed9ng hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1. = 2+1 = 3 4 4 (C\u00f3 th\u1ec3 tr\u00ecnh b\u00e0y b\u1eb1ng c\u00e1ch xu\u1ed1ng d\u00f2ng.) \u2013 Mu\u1ed1n c\u1ed9ng hai ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1, ta l\u00e0m th\u1ebf n\u00e0o? \u2013 GV \u0111\u1ecdc quy t\u1eafc trong SGK. 280","III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp Tr\u01b0\u1edbc khi luy\u1ec7n t\u1eadp, GV l\u01b0u \u00fd HS khi th\u1ef1c hi\u1ec7n ph\u00e9p c\u1ed9ng hai ph\u00e2n s\u1ed1. \u2013 X\u00e1c \u0111\u1ecbnh xem c\u00e1c ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1 hay kh\u00e1c m\u1eabu s\u1ed1. \u2022 N\u1ebfu c\u00f9ng m\u1eabu s\u1ed1, c\u1ed9ng t\u1eed s\u1ed1 v\u1edbi t\u1eed s\u1ed1, d\u01b0\u1edbi v\u1ea1ch ngang ch\u1ec9 vi\u1ebft m\u1ed9t m\u1eabu s\u1ed1 chung. \u2022 N\u1ebfu kh\u00e1c m\u1eabu s\u1ed1 \u2192 Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 \u2192 C\u1ed9ng hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1. \u2013 K\u1ebft qu\u1ea3 cu\u1ed1i c\u00f9ng l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. \u2013 S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c tr\u00f2 ch\u01a1i \u0111\u1ec3 c\u00e1c nh\u00f3m s\u1eeda b\u00e0i theo h\u00ecnh th\u1ee9c ti\u1ebfp s\u1ee9c. 2. Luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 GV l\u01b0u \u00fd HS \u00e1p d\u1ee5ng c\u00e1c t\u00ednh ch\u1ea5t c\u1ee7a ph\u00e9p c\u1ed9ng \u0111\u1ec3 t\u00ednh b\u1eb1ng c\u00e1ch thu\u1eadn ti\u1ec7n. \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. a) 1 + 1 + 1 b) 1 + 3 + 2 3 3 6 12 4 12 2 1 (112 2 3 = 3 + 6 = + 12 )+ 4 = 4 + 1 = 1 + 3 6 6 4 4 5 4 = 6 = 4 C\u0169ng c\u00f3 th\u1ec3 th\u1ef1c hi\u1ec7n nh\u01b0 sau: =1 1 + 1 + 1 = 2 + 2 + 1 c) 19 + 0 + 11 3 3 6 6 6 6 15 15 2+2+1 = 6 = 19 + 11 15 15 = 5 30 6 = 15 =2 IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 2: HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. \t B\u00e0i gi\u1ea3i \t 2 + 3 = 4 + 3 = 7 gi\u1edd, 5 10 10 10 10 xe 7 Sau hai t\u1ea3i ch\u1ea1y \u0111\u01b0\u1ee3c 10 qu\u00e3ng \u0111\u01b0\u1eddng. 281","B\u00e0i 70. EM L\u00c0M \u0110\u01af\u1ee2C NH\u1eeeNG G\u00cc? (1 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c ph\u00e9p c\u1ed9ng ph\u00e2n s\u1ed1 trong c\u00e1c tr\u01b0\u1eddng h\u1ee3p: c\u00e1c ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng m\u1eabu s\u1ed1; c\u00f3 m\u1ed9t m\u1eabu s\u1ed1 chia h\u1ebft cho c\u00e1c m\u1eabu s\u1ed1 c\u00f2n l\u1ea1i. \u2013 V\u1eadn d\u1ee5ng v\u00e0o gi\u1ea3i quy\u1ebft m\u1ed9t s\u1ed1 v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn ph\u00e9p c\u1ed9ng ph\u00e2n s\u1ed1 v\u00e0 bi\u1ec3u \u0111\u1ed3. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t tr\u00e1ch nhi\u1ec7m, nh\u00e2n \u00e1i. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh c\u00f3 trong b\u00e0i (n\u1ebfu c\u1ea7n). C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng C\u00f3 th\u1ec3 d\u00f9ng tr\u00f2 ch\u01a1i chuy\u1ec3n t\u1ea3i c\u00e1c n\u1ed9i dung sau: \u2013 C\u1ed9ng hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1. \u2013 C\u1ed9ng hai ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1 (trong \u0111\u00f3 c\u00f3 m\u1ed9t m\u1eabu s\u1ed1 chia h\u1ebft cho m\u1eabu s\u1ed1 kia). \u2026 II. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. \u2013 S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c tr\u00f2 ch\u01a1i \u0111\u1ec3 c\u00e1c nh\u00f3m s\u1eeda b\u00e0i theo h\u00ecnh th\u1ee9c ti\u1ebfp s\u1ee9c. III. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 2: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. \t B\u00e0i gi\u1ea3i 3 1 5 4 + 2 = 4 T\u00fai th\u1ee9 hai c\u00e2n n\u1eb7ng 5 kg. 4 \t\t 3 + 5 = 2 4 4 C\u1ea3 hai t\u00fai c\u00e2n n\u1eb7ng 2 kg. 282","B\u00e0i 3: \u2013 C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c \u0111\u1ec3 c\u00e1c nh\u00f3m GQV\u0110. \u2022 B\u01b0\u1edbc 1: T\u00ecm hi\u1ec3u v\u1ea5n \u0111\u1ec1 Nh\u1eadn bi\u1ebft v\u1ea5n \u0111\u1ec1 c\u1ea7n gi\u1ea3i quy\u1ebft: a) Thay .?. b\u1eb1ng s\u1ed1 th\u00edch h\u1ee3p. b) X\u00e1c \u0111\u1ecbnh ph\u00e2n s\u1ed1 l\u00e0 t\u1ed5ng c\u1ee7a hai trong ba ph\u00e2n s\u1ed1 c\u00f2n l\u1ea1i trong c\u00e1c ph\u00e2n s\u1ed1 \u1edf c\u00e2u a). \u2022 B\u01b0\u1edbc 2: L\u1eadp k\u1ebf ho\u1ea1ch N\u00eau \u0111\u01b0\u1ee3c c\u00e1ch th\u1ee9c GQV\u0110. D\u1ef1a v\u00e0o bi\u1ec3u \u0111\u1ed3 \u2192 T\u00ecm hi\u1ec3u bi\u1ec3u \u0111\u1ed3: Bi\u1ec3u \u0111\u1ed3 n\u00f3i v\u1ec1 c\u00e1i g\u00ec? D\u1ef1a v\u00e0o \u0111\u00e2u \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh \u0111\u1ed9 d\u00e0i m\u1ed7i b\u0103ng gi\u1ea5y? \u1ede c\u1ed9t s\u1ed1 b\u00ean tr\u00e1i, m\u1ed7i \u0111\u1ec1-xi-m\u00e9t \u0111\u01b0\u1ee3c chia th\u00e0nh m\u1ea5y ph\u1ea7n b\u1eb1ng nhau? a) D\u1ef1a v\u00e0o c\u1ed9t s\u1ed1 v\u00e0 c\u00e1c \u0111\u01b0\u1eddng k\u1ebb ngang, x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c \u0111\u1ed9 d\u00e0i m\u1ed7i b\u0103ng gi\u1ea5y. b) Ph\u00e2n s\u1ed1 l\u00e0 t\u1ed5ng c\u1ee7a hai trong ba ph\u00e2n s\u1ed1 c\u00f2n l\u1ea1i \u2192 D\u1ef1a v\u00e0o h\u00ecnh \u1ea3nh \u0111\u1ed9 d\u00e0i c\u00e1c b\u0103ng gi\u1ea5y ho\u1eb7c d\u1ef1a v\u00e0o vi\u1ec7c t\u00ednh to\u00e1n v\u1edbi c\u00e1c ph\u00e2n s\u1ed1. \u2022 B\u01b0\u1edbc 3: Ti\u1ebfn h\u00e0nh k\u1ebf ho\u1ea1ch C\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n v\u00e0 tr\u00ecnh b\u00e0y tr\u01b0\u1edbc l\u1edbp. 3 6 a) B\u0103ng gi\u1ea5y A: 10 dm\t\t\t B\u0103ng gi\u1ea5y B: 10 dm B\u0103ng gi\u1ea5y C: 4 dm\t\t\t B\u0103ng gi\u1ea5y D: 9 dm 10 10 9 3 6 b) 10 = 10 + 10 \u2022 B\u01b0\u1edbc 4: Ki\u1ec3m tra l\u1ea1i a) C\u00e1c ph\u00e2n s\u1ed1 c\u00f3 bi\u1ec3u th\u1ecb \u0111\u00fang \u0111\u1ed9 d\u00e0i c\u00e1c b\u0103ng gi\u1ea5y kh\u00f4ng? b) Vi\u1ec7c t\u00ednh to\u00e1n c\u00f3 \u0111\u00fang kh\u00f4ng? \u2013 GV h\u1ec7 th\u1ed1ng l\u1ea1i vi\u1ec7c l\u00e0m c\u1ee7a c\u00e1c nh\u00f3m. Th\u1eed th\u00e1ch Ho\u1ea1t \u0111\u1ed9ng nh\u00f3m. Khi tr\u00ecnh b\u00e0y, khuy\u1ebfn kh\u00edch c\u00e1c nh\u00f3m n\u00eau c\u00e1ch t\u00ecm c\u00e2u tr\u1ea3 l\u1eddi. Ch\u1eb3ng h\u1ea1n: Quy \u0111\u1ed3ng m\u1eabu s\u1ed1: 1 = 2 ; 1 ; 3 5 10 10 10 3 2 1 10 = 10 + 10 \u2192 Kh\u1ed1i l\u01b0\u1ee3ng c\u1ee7a g\u1ea5u n\u00e2u b\u1eb1ng t\u1ed5ng kh\u1ed1i l\u01b0\u1ee3ng c\u1ee7a g\u1ea5u \u0111en v\u00e0 g\u1ea5u ng\u1ef1a. 283","Ho\u1ea1t \u0111\u1ed9ng th\u1ef1c t\u1ebf Ho\u1ea1t \u0111\u1ed9ng nh\u00f3m. Tr\u00ecnh b\u00e0y. 1 + 3 = 2 + 3 2 4 4 = 5 4 5 Kh\u00f4ng x\u1ebfp \u0111\u01b0\u1ee3c hai ch\u1eadu hoa th\u00e0nh m\u1ed9t h\u00e0ng ngang tr\u00ean b\u1ec7 c\u1eeda s\u1ed5 v\u00ec 4 m > 1 m. B\u00e0i 71. TR\u1eea HAI PH\u00c2N S\u1ed0 C\u00d9NG M\u1eaaU S\u1ed0 (1 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS nh\u1eadn bi\u1ebft \u0111\u01b0\u1ee3c c\u00e1ch tr\u1eeb ph\u00e2n s\u1ed1, th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c ph\u00e9p tr\u1eeb ph\u00e2n s\u1ed1 trong tr\u01b0\u1eddng h\u1ee3p c\u00e1c ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng m\u1eabu s\u1ed1. \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn ph\u00e9p tr\u1eeb ph\u00e2n s\u1ed1. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t nh\u00e2n \u00e1i, ch\u0103m ch\u1ec9. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: H\u00ecnh \u1ea3nh ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng (n\u1ebfu c\u1ea7n). C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ho\u1ea1t \u0111\u1ed9ng nh\u00f3m. C\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n theo c\u00e1c y\u00eau c\u1ea7u sau: \u2013 Quan s\u00e1t h\u00ecnh v\u1ebd. \u2013 Vi\u1ebft ph\u00e9p t\u00ednh bi\u1ec3u th\u1ecb c\u00e1ch t\u00ecm ph\u1ea7n t\u1edd gi\u1ea5y \u0111\u00e3 t\u00f4 m\u00e0u nh\u01b0ng ch\u01b0a v\u1ebd hoa (s\u1ed1 b\u1ecb tr\u1eeb v\u00e0 s\u1ed1 tr\u1eeb l\u00e0 c\u00e1c ph\u00e2n s\u1ed1 d\u1ea1ng t\u1ed1i gi\u1ea3n). \u2013 D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd, t\u00ecm k\u1ebft qu\u1ea3 c\u1ee7a ph\u00e9p t\u00ednh tr\u00ean. \u2013 Th\u00f4ng b\u00e1o k\u1ebft qu\u1ea3 v\u00e0 gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. GV \u0111\u01b0a h\u00ecnh \u1ea3nh l\u00ean b\u1ea3ng. 8 2 Ph\u00e9p t\u00ednh c\u1ea7n vi\u1ebft: 15 \u2212 15 . D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd: 8 \u2212 2 = 6 = 2 . 15 15 15 5 GV \u0111\u1eb7t v\u1ea5n \u0111\u1ec1: Ta \u0111\u00e3 d\u1ef1a v\u00e0o h\u00ecnh v\u1ebd \u0111\u1ec3 t\u00ednh hi\u1ec7u c\u00e1c ph\u00e2n s\u1ed1, n\u1ebfu kh\u00f4ng c\u00f3 h\u00ecnh \u1ea3nh th\u00ec ta tr\u1eeb hai ph\u00e2n s\u1ed1 th\u1ebf n\u00e0o? \u2192 Gi\u1edbi thi\u1ec7u b\u00e0i m\u1edbi. 284","II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: Tr\u1eeb hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1 GV g\u1ee3i \u00fd, HS \u0111\u00f3ng g\u00f3p \u00fd ki\u1ebfn x\u00e2y d\u1ef1ng b\u00e0i. V\u00ed d\u1ee5: 8 \u2212 2 . 15 15 GV HS \u2013 Nh\u1eadn x\u00e9t m\u1eabu s\u1ed1 c\u1ee7a hai ph\u00e2n s\u1ed1. Hai ph\u00e2n s\u1ed1 c\u00f3 c\u00f9ng m\u1eabu s\u1ed1 l\u00e0 15. \u2013 D\u1ef1a v\u00e0o c\u00e1ch th\u1ef1c hi\u1ec7n ph\u00e9p c\u1ed9ng 8 \u2212 2 = 8\u22122 hai ph\u00e2n s\u1ed1, th\u1ef1c hi\u1ec7n ph\u00e9p tr\u1eeb n\u00e0y. 15 15 15 \u2013 K\u1ebft qu\u1ea3 ph\u00e9p t\u00ednh l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. = 6 \u2013 Mu\u1ed1n tr\u1eeb hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1, 15 2 ta l\u00e0m th\u1ebf n\u00e0o? = 5 So s\u00e1nh v\u1edbi k\u1ebft qu\u1ea3 \u1edf ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng. Tr\u1eeb hai t\u1eed s\u1ed1 v\u00e0 gi\u1eef nguy\u00ean m\u1eabu s\u1ed1. III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. C\u00f3 th\u1ec3 tr\u00ecnh b\u00e0y h\u00e0ng ngang nh\u01b0 SGK hay xu\u1ed1ng d\u00f2ng. 2. Luy\u1ec7n t\u1eadp Tr\u01b0\u1edbc khi luy\u1ec7n t\u1eadp, GV l\u01b0u \u00fd HS khi th\u1ef1c hi\u1ec7n ph\u00e9p tr\u1eeb hai ph\u00e2n s\u1ed1 c\u00f9ng ph\u00e2n s\u1ed1. \u2022 Tr\u1eeb t\u1eed s\u1ed1 v\u1edbi t\u1eed s\u1ed1, d\u01b0\u1edbi v\u1ea1ch ngang ch\u1ec9 vi\u1ebft m\u1ed9t m\u1eabu s\u1ed1 chung. \u2022 K\u1ebft qu\u1ea3 cu\u1ed1i c\u00f9ng l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 2: \u2013 HS \u0111\u1ecdc y\u00eau c\u1ea7u. \u2013 HS th\u1ea3o lu\u1eadn (nh\u00f3m \u0111\u00f4i) x\u00e1c \u0111\u1ecbnh c\u00e1c vi\u1ec7c c\u1ea7n l\u00e0m: Gi\u1ea3i b\u00e0i to\u00e1n theo t\u00f3m t\u1eaft. \u2013 S\u1eeda b\u00e0i: GV khuy\u1ebfn kh\u00edch nhi\u1ec1u nh\u00f3m tr\u00ecnh b\u00e0y c\u00e1ch l\u00e0m v\u00e0 n\u00f3i b\u00e0i to\u00e1n (ch\u1ec9 khuy\u1ebfn kh\u00edch nh\u1eefng HS c\u00f3 kh\u1ea3 n\u0103ng di\u1ec5n \u0111\u1ea1t t\u1ed1t). 7 1 V\u00ed d\u1ee5: S\u1ee3i d\u00e2y th\u1ee9 nh\u1ea5t d\u00e0i 8 m. S\u1ee3i d\u00e2y th\u1ee9 hai ng\u1eafn h\u01a1n s\u1ee3i d\u00e2y th\u1ee9 nh\u1ea5t 8 m. S\u1ee3i d\u00e2y th\u1ee9 ba ng\u1eafn h\u01a1n s\u1ee3i d\u00e2y th\u1ee9 hai 3 m. T\u00ednh chi\u1ec1u d\u00e0i s\u1ee3i d\u00e2y th\u1ee9 ba. 8 285","B\u00e0i gi\u1ea3i \t\t 7 \u2212 1 = 6 8 8 8 \t\u2009\u2009\u2009\u2009\u2009S\u1ee3i d\u00e2y th\u1ee9 hai d\u00e0i 6 m. 8 \t\t 6 \u2212 3 = 3 8 8 8 \t\u2009\u2009\u2009\u2009\u2009S\u1ee3i d\u00e2y th\u1ee9 ba d\u00e0i 3 m. 8 L\u01b0u \u00fd: HS c\u00f3 th\u1ec3 gi\u1ea3i b\u1eb1ng c\u00e1ch kh\u00e1c, n\u1ebfu \u0111\u00fang \u2192 c\u00f4ng nh\u1eadn. Khi \u0111\u00f3, GV c\u00f3 th\u1ec3 cho HS so s\u00e1nh c\u00e1c c\u00e1ch gi\u1ea3i \u2192 ch\u1ecdn c\u00e1ch gi\u1ea3i d\u1ec5 h\u01a1n. B\u00e0i 72. TR\u1eea HAI PH\u00c2N S\u1ed0 KH\u00c1C M\u1eaaU S\u1ed0 (1 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c ph\u00e9p tr\u1eeb ph\u00e2n s\u1ed1 trong tr\u01b0\u1eddng h\u1ee3p c\u00f3 m\u1ed9t m\u1eabu s\u1ed1 chia h\u1ebft cho c\u00e1c m\u1eabu s\u1ed1 c\u00f2n l\u1ea1i. \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn ph\u00e9p tr\u1eeb ph\u00e2n s\u1ed1. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t nh\u00e2n \u00e1i, ch\u0103m ch\u1ec9. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: H\u00ecnh \u1ea3nh ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng (n\u1ebfu c\u1ea7n). C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ho\u1ea1t \u0111\u1ed9ng nh\u00f3m. C\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n theo c\u00e1c y\u00eau c\u1ea7u sau: \u2013 Quan s\u00e1t h\u00ecnh v\u1ebd. \u2013 Vi\u1ebft ph\u00e9p t\u00ednh bi\u1ec3u th\u1ecb c\u00e1ch t\u00ecm ph\u1ea7n t\u1edd gi\u1ea5y \u0111\u00e3 t\u00f4 m\u00e0u nh\u01b0ng kh\u00f4ng v\u1ebd hoa (s\u1ed1 b\u1ecb tr\u1eeb v\u00e0 s\u1ed1 tr\u1eeb l\u00e0 c\u00e1c ph\u00e2n s\u1ed1 d\u1ea1ng t\u1ed1i gi\u1ea3n). \u2013 D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd, t\u00ecm k\u1ebft qu\u1ea3 c\u1ee7a ph\u00e9p t\u00ednh tr\u00ean. \u2013 Th\u00f4ng b\u00e1o k\u1ebft qu\u1ea3 v\u00e0 gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. GV \u0111\u01b0a h\u00ecnh \u1ea3nh l\u00ean b\u1ea3ng. Ph\u00e9p t\u00ednh c\u1ea7n vi\u1ebft: 3 \u2212 2 . 5 15 3 2 7 D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd: 5 \u2212 15 = 15 . 286","GV \u0111\u1eb7t v\u1ea5n \u0111\u1ec1: Ta \u0111\u00e3 d\u1ef1a v\u00e0o h\u00ecnh v\u1ebd \u0111\u1ec3 t\u00ednh hi\u1ec7u c\u00e1c ph\u00e2n s\u1ed1, n\u1ebfu kh\u00f4ng c\u00f3 h\u00ecnh \u1ea3nh th\u00ec ta tr\u1eeb hai ph\u00e2n s\u1ed1 th\u1ebf n\u00e0o? \u2192 B\u00e0i m\u1edbi. II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: Tr\u1eeb hai ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1 GV g\u1ee3i \u00fd, HS \u0111\u00f3ng g\u00f3p \u00fd ki\u1ebfn x\u00e2y d\u1ef1ng b\u00e0i. V\u00ed d\u1ee5: 3 \u2013 2 . 5 15 GV HS \u2013 Nh\u1eadn x\u00e9t m\u1eabu s\u1ed1 c\u1ee7a hai ph\u00e2n s\u1ed1. \u2013 D\u1ef1a v\u00e0o c\u00e1ch th\u1ef1c hi\u1ec7n ph\u00e9p c\u1ed9ng Hai ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1. hai ph\u00e2n s\u1ed1, th\u1ef1c hi\u1ec7n ph\u00e9p tr\u1eeb n\u00e0y. \u2009\u2009\u2009 3 \u2212 2 = 9 \u2212 2 5 15 15 15 \u2013 K\u1ebft qu\u1ea3 ph\u00e9p t\u00ednh l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. \u2009\u2009\u2009 = 9\u22122 \u2013 Mu\u1ed1n tr\u1eeb hai ph\u00e2n s\u1ed1 kh\u00e1c m\u1eabu s\u1ed1 15 ta l\u00e0m th\u1ebf n\u00e0o? 8 \u2009\u2009\u2009 = 15 So s\u00e1nh v\u1edbi k\u1ebft qu\u1ea3 \u1edf ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng. Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 r\u1ed3i tr\u1eeb hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1. III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp Tr\u01b0\u1edbc khi luy\u1ec7n t\u1eadp, GV l\u01b0u \u00fd HS khi th\u1ef1c hi\u1ec7n ph\u00e9p tr\u1eeb hai ph\u00e2n s\u1ed1. \u2013 X\u00e1c \u0111\u1ecbnh xem c\u00e1c ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1 hay kh\u00e1c m\u1eabu s\u1ed1. \u2022 N\u1ebfu c\u00f9ng m\u1eabu s\u1ed1 \u2192 Tr\u1eeb t\u1eed s\u1ed1 v\u1edbi t\u1eed s\u1ed1, d\u01b0\u1edbi v\u1ea1ch ngang ch\u1ec9 vi\u1ebft m\u1ed9t m\u1eabu s\u1ed1 chung. \u2022 N\u1ebfu kh\u00e1c m\u1eabu s\u1ed1 \u2192 Quy \u0111\u1ed3ng m\u1eabu s\u1ed1 \u2192 Tr\u1eeb hai ph\u00e2n s\u1ed1 c\u00f9ng m\u1eabu s\u1ed1. \u2013 K\u1ebft qu\u1ea3 cu\u1ed1i c\u00f9ng l\u00e0 ph\u00e2n s\u1ed1 t\u1ed1i gi\u1ea3n. 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. \u2013 S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c tr\u00f2 ch\u01a1i \u0111\u1ec3 c\u00e1c nh\u00f3m s\u1eeda b\u00e0i theo h\u00ecnh th\u1ee9c ti\u1ebfp s\u1ee9c. 2. Luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m. \u2013 GV l\u01b0u \u00fd HS: Th\u1ee9 t\u1ef1 th\u1ef1c hi\u1ec7n ph\u00e9p t\u00ednh v\u1edbi c\u00e1c ph\u00e2n s\u1ed1 gi\u1ed1ng nh\u01b0 th\u1ee9 t\u1ef1 th\u1ef1c hi\u1ec7n ph\u00e9p t\u00ednh v\u1edbi s\u1ed1 t\u1ef1 nhi\u00ean. 287","\u2013 S\u1eeda b\u00e0i. a) 3 \u2212 1 \u2212 5 = 9 \u2212 1 \u2212 5 b) 1\u2212 1 \u2212 2 = 3 \u2212 1 \u2212 2 2 6 6 6 6 6 3 3 3 3 3 = 8 \u2212 5 = 2 \u2212 2 6 6 3 3 = 3 =0 6 = 1 2 IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 2: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, HS n\u00f3i c\u00e1ch l\u00e0m. B\u00e0i gi\u1ea3i 1 \u2212 1 = 1 3 6 6 1 Hoa m\u00e0u \u0111\u1ecf nhi\u1ec1u h\u01a1n hoa m\u00e0u t\u00edm l\u00e0 6 s\u1ed1 hoa c\u1ee7a b\u00ecnh. B\u00e0i 73. EM L\u00c0M \u0110\u01af\u1ee2C NH\u1eeeNG G\u00cc? (2 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS th\u1ef1c hi\u1ec7n vi\u1ec7c c\u1ed9ng, tr\u1eeb ph\u00e2n s\u1ed1 \u0111\u1ec3 t\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c; t\u00ecm th\u00e0nh ph\u1ea7n trong ph\u00e9p t\u00ednh c\u1ed9ng, tr\u1eeb. \u2013 V\u1eadn d\u1ee5ng v\u00e0o gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 \u0111\u1ed1i v\u1edbi c\u1ed9ng, tr\u1eeb ph\u00e2n s\u1ed1 trong \u0111\u00f3 c\u00f3 m\u1ed9t gi\u00e1 tr\u1ecb l\u00e0 1; gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn c\u1ed9ng, tr\u1eeb ph\u00e2n s\u1ed1. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc, giao ti\u1ebfp to\u00e1n h\u1ecdc, m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c, gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t ch\u0103m ch\u1ec9, nh\u00e2n \u00e1i. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh s\u1eed d\u1ee5ng \u1edf b\u00e0i Luy\u1ec7n t\u1eadp 2, 3 v\u00e0 Th\u1eed th\u00e1ch (n\u1ebfu c\u1ea7n). C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ch\u01a1i tr\u00f2 ch\u01a1i \u201cT\u00f4i b\u1ea3o\u201d. \u2013 GV: T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? 288","\u2013 GV: T\u00f4i b\u1ea3o: C\u00f3 m\u1ed9t h\u1ed9p k\u1eb9o, cu T\u00ed \u0111\u00e3 \u0103n h\u1ebft 1 s\u1ed1 k\u1eb9o trong h\u1ed9p. C\u00e1c b\u1ea1n vi\u1ebft ph\u00e9p 3 t\u00ednh r\u1ed3i t\u00ednh s\u1ed1 k\u1eb9o c\u00f2n l\u1ea1i trong h\u1ed9p. \u2013 HS vi\u1ebft v\u00e0o b\u1ea3ng con: 1\u2212 1 = 2 (h\u1ed9p k\u1eb9o). 3 3 \u2013 GV: T\u00f4i b\u1ea3o! T\u00f4i b\u1ea3o! \u2013 HS: B\u1ea3o g\u00ec? B\u1ea3o g\u00ec? 3 c\u00f4ng vi\u1ec7c \u0111\u01b0\u1ee3c giao. C\u00e1c b\u1ea1n vi\u1ebft ph\u00e9p t\u00ednh r\u1ed3i t\u00ednh \u2013 GV: T\u00f4i b\u1ea3o: Cu T\u00e8o \u0111\u00e3 l\u00e0m \u0111\u01b0\u1ee3c 4 ph\u1ea7n vi\u1ec7c cu T\u00e8o ch\u01b0a l\u00e0m. 3 1 4 4 \u2013 HS vi\u1ebft v\u00e0o b\u1ea3ng con: 1 \u2212 = (c\u00f4ng vi\u1ec7c). II. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n: Nh\u1eadn bi\u1ebft th\u1ee9 t\u1ef1 th\u1ef1c hi\u1ec7n ph\u00e9p t\u00ednh r\u1ed3i t\u00ednh to\u00e1n. \u2013 S\u1eeda b\u00e0i, HS tr\u00ecnh b\u00e0y t\u1eebng b\u01b0\u1edbc t\u00ednh. B\u00e0i 2: \u2013 C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c \u0111\u1ec3 c\u00e1c nh\u00f3m GQV\u0110. B\u01b0\u1edbc 1: T\u00ecm hi\u1ec3u v\u1ea5n \u0111\u1ec1 Nh\u1eadn bi\u1ebft v\u1ea5n \u0111\u1ec1 c\u1ea7n gi\u1ea3i quy\u1ebft: a) Thay .?. b\u1eb1ng s\u1ed1 th\u00edch h\u1ee3p. b) Thay .?. b\u1eb1ng s\u1ed1 th\u00edch h\u1ee3p. B\u01b0\u1edbc 2: L\u1eadp k\u1ebf ho\u1ea1ch N\u00eau \u0111\u01b0\u1ee3c c\u00e1ch th\u1ee9c GQV\u0110. D\u1ef1a v\u00e0o bi\u1ec3u \u0111\u1ed3 \u2192 T\u00ecm hi\u1ec3u bi\u1ec3u \u0111\u1ed3: Bi\u1ec3u \u0111\u1ed3 n\u00f3i v\u1ec1 c\u00e1i g\u00ec? D\u1ef1a v\u00e0o \u0111\u00e2u \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh ph\u1ea7n hoa m\u1ed7i m\u00e0u? \u1ede c\u1ed9t s\u1ed1 b\u00ean tr\u00e1i, h\u1ed9p hoa \u0111\u01b0\u1ee3c chia th\u00e0nh m\u1ea5y ph\u1ea7n b\u1eb1ng nhau? a) D\u1ef1a v\u00e0o c\u1ed9t s\u1ed1 v\u00e0 c\u00e1c \u0111\u01b0\u1eddng k\u1ebb ngang, x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c ph\u1ea7n hoa bi\u1ec3u th\u1ecb theo \u0111\u01a1n v\u1ecb \u201ch\u1ed9p\u201d. b) T\u00ecm hi\u1ec7u gi\u1eefa ph\u1ea7n hoa m\u00e0u v\u00e0ng v\u00e0 m\u00e0u \u0111\u1ecf; t\u00ecm t\u1ed5ng ph\u1ea7n hoa c\u1ea3 ba m\u00e0u. \u2192 D\u1ef1a v\u00e0o bi\u1ec3u \u0111\u1ed3 ho\u1eb7c d\u1ef1a v\u00e0o vi\u1ec7c t\u00ednh to\u00e1n v\u1edbi c\u00e1c ph\u00e2n s\u1ed1. B\u01b0\u1edbc 3: Ti\u1ebfn h\u00e0nh k\u1ebf ho\u1ea1ch C\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n v\u00e0 tr\u00ecnh b\u00e0y tr\u01b0\u1edbc l\u1edbp. 1 a) Ph\u1ea7n hoa m\u00e0u \u0111\u1ecf b\u1eb1ng 6 h\u1ed9p. 289","Ph\u1ea7n hoa m\u00e0u h\u1ed3ng b\u1eb1ng 1 h\u1ed9p. 2 Ph\u1ea7n hoa m\u00e0u v\u00e0ng b\u1eb1ng 1 h\u1ed9p. 3 b) Ph\u1ea7n hoa m\u00e0u \u0111\u1ecf \u00edt h\u01a1n ph\u1ea7n hoa m\u00e0u v\u00e0ng l\u00e0 1 h\u1ed9p. 6 1 1 1 (Quan s\u00e1t tr\u00ean bi\u1ec3u \u0111\u1ed3 ho\u1eb7c 3 \u2212 6 = 6 .) T\u1ed5ng s\u1ed1 ph\u1ea7n hoa c\u1ea3 ba m\u00e0u l\u00e0 1 h\u1ed9p. 1 1 1 (Quan s\u00e1t tr\u00ean bi\u1ec3u \u0111\u1ed3 ho\u1eb7c 6 + 2 + 3 = 1 .) B\u01b0\u1edbc 4: Ki\u1ec3m tra l\u1ea1i a) C\u00e1c ph\u00e2n s\u1ed1 c\u00f3 bi\u1ec3u th\u1ecb \u0111\u00fang ph\u1ea7n hoa m\u1ed7i m\u00e0u so v\u1edbi 1 h\u1ed9p kh\u00f4ng? Vi\u1ec7c t\u00ednh to\u00e1n c\u00f3 \u0111\u00fang kh\u00f4ng? \u2013 GV h\u1ec7 th\u1ed1ng l\u1ea1i vi\u1ec7c l\u00e0m c\u1ee7a c\u00e1c nh\u00f3m. B\u00e0i 3: \u2013 HS ho\u1ea1t \u0111\u1ed9ng nh\u00f3m \u0111\u00f4i. Nh\u1eadn bi\u1ebft: L\u00fac \u0111\u1ea7u \u0111\u1ea7y b\u1ec3 (1 b\u1ec3) \u2192 \u0110\u00e3 d\u00f9ng l\u00e0 ph\u1ea7n m\u00e0u tr\u1eafng \u2192 C\u00f2n l\u1ea1i l\u00e0 ph\u1ea7n m\u00e0u xanh. \u2013 S\u1eeda b\u00e0i, HS gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. Ch\u1eb3ng h\u1ea1n: 2 2 1 3 3 3 B\u1ec3 1: 1 b\u1ec3 n\u01b0\u1edbc \u0111\u1ea7y, \u0111\u00e3 d\u00f9ng b\u1ec3 \u2192 C\u00f2n l\u1ea1i: 1\u2212 = \u2192 Ch\u1ecdn B. \u2026 B\u00e0i 4: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. L\u01b0u \u00fd: HS c\u00f3 th\u1ec3 t\u00ecm s\u1ed1 theo c\u00e1c c\u00e1ch kh\u00e1c nhau. Ch\u1eb3ng h\u1ea1n: a) 1 + .?. = 3 4 4 \u00c1p d\u1ee5ng quy t\u1eafc t\u00ecm s\u1ed1 h\u1ea1ng. 1 2 3 1 1 3 Ho\u1eb7c nh\u1ea9m: 4 + 4 = 4 \u2192 4 + 2 = 4 . B\u00e0i 5: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n, chia s\u1ebb nh\u00f3m b\u1ed1n. 290","\u2013 S\u1eeda b\u00e0i: B\u00e0i gi\u1ea3i 1 + 1 = 3 2 4 4 Trong hai tu\u1ea7n, gia \u0111\u00ecnh Li\u00ean \u0111\u00e3 d\u00f9ng h\u1ebft 3 l\u1ecd \u0111\u01b0\u1eddng. 4 1\u2212 3 = 1 4 4 C\u00f2n l\u1ea1i 1 l\u1ecd \u0111\u01b0\u1eddng. 4 III. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m Th\u1eed th\u00e1ch C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c cho c\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n r\u1ed3i thi \u0111ua. S\u1eeda b\u00e0i, GV h\u1ec7 th\u1ed1ng c\u00e1ch th\u1ee9c GQV\u0110. Ch\u1eb3ng h\u1ea1n: \u2022 Th\u1ed1ng nh\u1ea5t \u0111\u01a1n v\u1ecb. N\u1ebfu coi \u0111\u01a1n v\u1ecb l\u00e0 m\u1ed9t \u00f4 vu\u00f4ng nh\u1ecf th\u00ec: 2 m\u1ea3nh tam gi\u00e1c nh\u1ecf t\u1ea1o th\u00e0nh 1 \u00f4 vu\u00f4ng. \u2013 Vi\u00ean g\u1ea1ch g\u1ed3m 16 \u00f4 vu\u00f4ng (\u0111\u1ebfm ho\u1eb7c t\u00ednh: 4 \u00d7 4 = 16). \u2013 Ph\u1ea7n m\u00e0u v\u00e0ng g\u1ed3m 2 \u00f4 vu\u00f4ng. \u2013 Ph\u1ea7n m\u00e0u xanh \u0111\u1eadm g\u1ed3m 6 \u00f4 vu\u00f4ng. \u2013 Ph\u1ea7n m\u00e0u xanh nh\u1ea1t g\u1ed3m 8 \u00f4 vu\u00f4ng. \u2022 Vi\u1ebft ph\u00e2n s\u1ed1 ch\u1ec9 t\u1eebng m\u00e0u so v\u1edbi vi\u00ean g\u1ea1ch. 1 vi\u00ean g\u1ea1ch l\u00e0 m\u00e0u v\u00e0ng. ( 2 = 1 ) 8 16 8 3 vi\u00ean g\u1ea1ch l\u00e0 m\u00e0u xanh \u0111\u1eadm. ( 6 = 3 ) 8 16 8 1 vi\u00ean g\u1ea1ch l\u00e0 m\u00e0u xanh nh\u1ea1t. ( 8 = 1 ) 2 16 2 \u2022 T\u1ed5ng hai ph\u00e2n s\u1ed1 ch\u1ec9 ph\u1ea7n g\u1ea1ch m\u00e0u v\u00e0ng v\u00e0 m\u00e0u xanh \u0111\u1eadm b\u1eb1ng ph\u00e2n s\u1ed1 ch\u1ec9 ph\u1ea7n 1 3 4 1 g\u1ea1ch m\u00e0u xanh nh\u1ea1t. ( 8 + 8 = 8 = 2 ) Ho\u1ea1t \u0111\u1ed9ng th\u1ef1c t\u1ebf GV nh\u1eafc HS, n\u1ebfu c\u00f3 \u0111i\u1ec1u ki\u1ec7n, l\u00e0m theo h\u01b0\u1edbng d\u1eabn \u1edf m\u1ee5c n\u00e0y. 291","B\u00e0i 74. PH\u00c9P NH\u00c2N PH\u00c2N S\u1ed0 (2 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS nh\u1eadn bi\u1ebft \u0111\u01b0\u1ee3c c\u00e1ch nh\u00e2n hai ph\u00e2n s\u1ed1; th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c ph\u00e9p nh\u00e2n hai ph\u00e2n s\u1ed1. \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn c\u00e1c ph\u00e9p t\u00ednh c\u1ed9ng, tr\u1eeb, nh\u00e2n c\u00e1c ph\u00e2n s\u1ed1. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc; giao ti\u1ebfp to\u00e1n h\u1ecdc; m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c; s\u1eed d\u1ee5ng c\u00f4ng c\u1ee5, ph\u01b0\u01a1ng ti\u1ec7n h\u1ecdc to\u00e1n; gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t ch\u0103m ch\u1ec9, tr\u00e1ch nhi\u1ec7m. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh c\u00f3 trong b\u00e0i (n\u1ebfu c\u1ea7n). HS: Gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng. C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ho\u1ea1t \u0111\u1ed9ng nh\u00f3m. C\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n theo c\u00e1c y\u00eau c\u1ea7u sau: \u2013 \u0110\u1ecdc c\u00e1c th\u00f4ng tin trong ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng. 3 1 \u2013 Vi\u1ebft ph\u00e9p t\u00ednh t\u00ecm di\u1ec7n t\u00edch m\u1ea3nh v\u1ea3i. ( 4 \u00d7 2 ) \u2013 D\u00f9ng gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng, th\u1ef1c hi\u1ec7n vi\u1ec7c t\u00ecm di\u1ec7n t\u00edch: C\u1ea7n v\u1ebd m\u1ed9t h\u00ecnh vu\u00f4ng th\u1ec3 hi\u1ec7n 1 m2. D\u1ef1a v\u00e0o chi\u1ec1u d\u00e0i v\u00e0 chi\u1ec1u r\u1ed9ng c\u1ee7a m\u1ea3nh v\u1ea3i \u0111\u1ec3 xem n\u00ean chia c\u1ea1nh h\u00ecnh vu\u00f4ng tr\u00ean th\u00e0nh m\u1ea5y ph\u1ea7n b\u1eb1ng nhau. T\u00f4 m\u00e0u ph\u1ea7n bi\u1ec3u th\u1ecb m\u1ea3nh v\u1ea3i. 1m D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd, t\u00ecm di\u1ec7n t\u00edch m\u1ea3nh v\u1ea3i. \u2013 Th\u00f4ng b\u00e1o k\u1ebft qu\u1ea3 v\u00e0 gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. \u2013 GV treo (ho\u1eb7c tr\u00ecnh chi\u1ebfu) h\u00ecnh \u1ea3nh l\u00ean b\u1ea3ng. Di\u1ec7n t\u00edch h\u00ecnh vu\u00f4ng l\u1edbn: 1 m2. 1m 1 Di\u1ec7n t\u00edch 1 \u00f4 vu\u00f4ng: 16 m2. 1 m 2 6 3 Di\u1ec7n t\u00edch m\u1ea3nh v\u1ea3i: 16 m2 hay 8 m2. \u2192 3 \u00d7 1 = 3 3 m 4 2 8 4 \u2013 GV \u0111\u1eb7t v\u1ea5n \u0111\u1ec1: Ta \u0111\u00e3 d\u1ef1a v\u00e0o h\u00ecnh v\u1ebd \u0111\u1ec3 t\u00ednh di\u1ec7n t\u00edch h\u00ecnh ch\u1eef nh\u1eadt. N\u1ebfu kh\u00f4ng c\u00f3 h\u00ecnh v\u1ebd th\u00ec th\u1ef1c hi\u1ec7n c\u00e1ch n\u00e0o? \u2192 Gi\u1edbi thi\u1ec7u b\u00e0i m\u1edbi. 292","II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: Ph\u00e9p nh\u00e2n ph\u00e2n s\u1ed1 Th\u1ef1c hi\u1ec7n ph\u00e9p nh\u00e2n hai ph\u00e2n s\u1ed1 \u2013 GV vi\u1ebft b\u1ea3ng: 3 \u00d7 1 = 3 4 2 8 \u2013 Nh\u1eadn x\u00e9t s\u1ef1 li\u00ean quan gi\u1eefa: T\u1eed s\u1ed1 c\u1ee7a k\u1ebft qu\u1ea3 v\u00e0 t\u1eed s\u1ed1 c\u1ee7a hai th\u1eeba s\u1ed1. (3 = 3 \u00d7 1) M\u1eabu s\u1ed1 c\u1ee7a k\u1ebft qu\u1ea3 v\u00e0 m\u1eabu s\u1ed1 c\u1ee7a hai th\u1eeba s\u1ed1. (8 = 4 \u00d7 2) \u2013 V\u1eady khi nh\u00e2n hai ph\u00e2n s\u1ed1, ta th\u1ef1c hi\u1ec7n th\u1ebf n\u00e0o? (Nh\u00e2n t\u1eed s\u1ed1 v\u1edbi t\u1eed s\u1ed1, nh\u00e2n m\u1eabu s\u1ed1 v\u1edbi m\u1eabu s\u1ed1.) GV vi\u1ebft = 3 \u00d71 v\u00e0o ch\u1ed7 tr\u1ed1ng \u1edf ph\u00e9p t\u00ednh tr\u00ean. 4 \u00d72 III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 T\u00ecm hi\u1ec3u m\u1eabu. H\u00ecnh ch\u1eef nh\u1eadt l\u1edbn c\u00f3 chi\u1ec1u d\u00e0i l\u00e0 4 \u00f4, chi\u1ec1u r\u1ed9ng l\u00e0 3 \u00f4. 3 Ph\u1ea7n h\u00ecnh \u0111\u01b0\u1ee3c t\u00f4 m\u00e0u c\u00f3 chi\u1ec1u r\u1ed9ng b\u1eb1ng 2 chi\u1ec1u r\u1ed9ng c\u1ee7a h\u00ecnh l\u1edbn, chi\u1ec1u d\u00e0i b\u1eb1ng 4 chi\u1ec1u d\u00e0i c\u1ee7a h\u00ecnh l\u1edbn. 3 Ph\u1ea7n h\u00ecnh t\u00f4 m\u00e0u \u0111\u01b0\u1ee3c t\u00ednh nh\u01b0 sau: 2 \u00d7 3 = 2\u00d7 31 = 1 . 3 4 31 \u00d7 4 2 GV l\u01b0u \u00fd HS n\u00ean r\u00fat g\u1ecdn ngay \u1edf b\u01b0\u1edbc th\u1ee9 hai. HS c\u00f3 th\u1ec3 d\u00f9ng b\u00fat ch\u00ec g\u1ea1ch v\u00e0o c\u00e1c s\u1ed1 \u0111\u01b0\u1ee3c r\u00fat g\u1ecdn (nh\u01b0 \u1edf tr\u00ean). Ki\u1ec3m tra l\u1ea1i xem ph\u1ea7n h\u00ecnh \u0111\u01b0\u1ee3c t\u00f4 m\u00e0u c\u00f3 \u0111\u00fang b\u1eb1ng 1 h\u00ecnh l\u1edbn ban \u0111\u1ea7u kh\u00f4ng. 2 D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd: N\u1ebfu s\u1eafp x\u1ebfp l\u1ea1i h\u00ecnh \u1ea3nh nh\u01b0 sau th\u00ec h\u00ecnh ban \u0111\u1ea7u \u0111\u01b0\u1ee3c chia th\u00e0nh 2 ph\u1ea7n b\u1eb1ng nhau, 1 h\u00ecnh m\u00e0u xanh l\u00e0 1 ph\u1ea7n t\u1ee9c l\u00e0 2 h\u00ecnh. \u2013 HS th\u1ef1c h\u00e0nh nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, GV khuy\u1ebfn kh\u00edch HS tr\u00ecnh b\u00e0y c\u00e1ch l\u00e0m. 293","C\u00e2u b) x\u1ebfp l\u1ea1i h\u00ecnh nh\u01b0 sau: \t\t\t C\u00e2u c) x\u1ebfp l\u1ea1i h\u00ecnh nh\u01b0 sau: \t\t \t\t\t 2. Luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n r\u1ed3i chia s\u1ebb nh\u00f3m \u0111\u00f4i. L\u01b0u \u00fd: HS n\u00ean r\u00fat g\u1ecdn ngay t\u1eeb b\u01b0\u1edbc th\u1ee9 hai. B\u00e0i 2: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e2u a), GV s\u1eeda b\u00e0i r\u1ed3i gi\u1edbi thi\u1ec7u c\u00e1ch vi\u1ebft ng\u1eafn g\u1ecdn. 3 2\u00d73 3 \t\t 2\u00d7 14 = 14 = 7 \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1c c\u00e2u c\u00f2n l\u1ea1i (n\u00ean tr\u00ecnh b\u00e0y theo c\u00e1ch ng\u1eafn g\u1ecdn). \u2013 S\u1eeda b\u00e0i, l\u01b0u \u00fd HS k\u1ebft qu\u1ea3 c\u1ee7a ph\u00e9p nh\u00e2n ph\u00e2n s\u1ed1 v\u1edbi 0. B\u00e0i 3: \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n r\u1ed3i chia s\u1ebb nh\u00f3m \u0111\u00f4i. 2 2 7 Sau khi s\u1eeda b\u00e0i, GV l\u01b0u \u00fd HS nh\u1eadn bi\u1ebft 7 \u00d7 3 l\u00e0 t\u1ed5ng c\u1ee7a ba ph\u00e2n s\u1ed1 b\u1eb1ng nhau ( ). V. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 4: \u2013 HS ho\u1ea1t \u0111\u1ed9ng nh\u00f3m b\u1ed1n. \u2013 GV l\u01b0u \u00fd HS: \u2022 Th\u1ee9 t\u1ef1 th\u1ef1c hi\u1ec7n ph\u00e9p t\u00ednh v\u1edbi c\u00e1c ph\u00e2n s\u1ed1 gi\u1ed1ng nh\u01b0 th\u1ee9 t\u1ef1 th\u1ef1c hi\u1ec7n ph\u00e9p t\u00ednh v\u1edbi c\u00e1c s\u1ed1 t\u1ef1 nhi\u00ean. \u2022 N\u00ean ph\u00e2n c\u00f4ng m\u1ed7i HS trong nh\u00f3m t\u00ednh gi\u00e1 tr\u1ecb m\u1ed9t bi\u1ec3u th\u1ee9c \u1edf h\u00e0ng tr\u00ean \u2192 D\u1ef1 \u0111o\u00e1n gi\u00e1 tr\u1ecb \u0111\u00f3 b\u1eb1ng gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c n\u00e0o \u1edf h\u00e0ng d\u01b0\u1edbi \u2192 T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c \u0111\u00f3 \u2192 K\u1ebft lu\u1eadn. \u2013 Sau khi s\u1eeda b\u00e0i, GV gi\u00fap HS nh\u1eadn x\u00e9t (SGK). 294","B\u00e0i 5: \u2013 GV l\u01b0u \u00fd HS \u00e1p d\u1ee5ng c\u00e1c t\u00ednh ch\u1ea5t c\u1ee7a ph\u00e9p t\u00ednh \u0111\u1ec3 th\u1ef1c hi\u1ec7n theo c\u00e1ch thu\u1eadn ti\u1ec7n. \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n r\u1ed3i chia s\u1ebb nh\u00f3m \u0111\u00f4i. \u2013 S\u1eeda b\u00e0i, GV khuy\u1ebfn kh\u00edch HS n\u00f3i c\u00e1ch l\u00e0m. a) 7 \u00d7 15 \u00d7 9 b) 9 \u00d7 \uf8eb 2 \u00d7 14 \uf8f6 9 28 7 32 \uf8ec\uf8ed 3 21 \uf8f8\uf8f7 = \uf8eb 7 \u00d7 9 \uf8f6 \u00d7 15 = 9 \u00d7 \uf8eb 2 \u00d7 2 \uf8f6 \uf8ed\uf8ec 9 7 \uf8f8\uf8f7 28 32 \uf8ed\uf8ec 3 3 \uf8f7\uf8f8 = 1\u00d7 15 = 9 \u00d7 4 28 32 9 = 15 = 9\u00d74 28 32 \u00d7 9 = 1 8 B\u00e0i 6: \u2013 C\u00f3 th\u1ec3 t\u1ed5 ch\u1ee9c \u0111\u1ec3 c\u00e1c nh\u00f3m GQV\u0110. \u2022 B\u01b0\u1edbc 1: T\u00ecm hi\u1ec3u v\u1ea5n \u0111\u1ec1 Nh\u1eadn bi\u1ebft v\u1ea5n \u0111\u1ec1 c\u1ea7n gi\u1ea3i quy\u1ebft: T\u00ecm di\u1ec7n t\u00edch ph\u1ea7n m\u00e0u v\u00e0ng theo \u0111\u01a1n v\u1ecb m\u00e9t vu\u00f4ng. \u2022 B\u01b0\u1edbc 2: L\u1eadp k\u1ebf ho\u1ea1ch N\u00eau \u0111\u01b0\u1ee3c c\u00e1ch th\u1ee9c GQV\u0110. C\u00e1ch 1: Ph\u00e2n t\u00edch: \u0110\u1ec3 t\u00ednh \u0111\u01b0\u1ee3c di\u1ec7n t\u00edch ph\u1ea7n m\u00e0u v\u00e0ng \u2192 L\u1ea5y Di\u1ec7n t\u00edch h\u00ecnh ch\u1eef nh\u1eadt t\u00f4 m\u00e0u \u2013 Di\u1ec7n t\u00edch h\u00ecnh vu\u00f4ng m\u00e0u xanh \u2192 Bi\u1ebft chi\u1ec1u d\u00e0i, chi\u1ec1u r\u1ed9ng h\u00ecnh ch\u1eef nh\u1eadt t\u00f4 m\u00e0u; s\u1ed1 \u0111o c\u1ea1nh h\u00ecnh vu\u00f4ng m\u00e0u xanh \u2192 D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd. C\u00e1ch 2: \u0110\u1ebfm s\u1ed1 \u00f4 vu\u00f4ng \u1edf h\u00ecnh m\u00e0u v\u00e0ng. \u2192 Ph\u00e2n s\u1ed1 ch\u1ec9 ph\u1ea7n t\u00f4 m\u00e0u v\u00e0ng tr\u00ean c\u1ea3 h\u00ecnh vu\u00f4ng c\u1ea1nh 1 m \u2192 T\u00ecm di\u1ec7n t\u00edch h\u00ecnh vu\u00f4ng c\u1ea1nh 1 m v\u00e0 s\u1ed1 \u00f4 vu\u00f4ng c\u1ee7a c\u1ea3 h\u00ecnh vu\u00f4ng n\u00e0y. \u2022 B\u01b0\u1edbc 3: Ti\u1ebfn h\u00e0nh k\u1ebf ho\u1ea1ch C\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n v\u00e0 tr\u00ecnh b\u00e0y tr\u01b0\u1edbc l\u1edbp. C\u00e1ch 1: C\u1ea1nh h\u00ecnh vu\u00f4ng l\u1edbn l\u00e0 1 m, \u0111\u01b0\u1ee3c chia th\u00e0nh 10 ph\u1ea7n b\u1eb1ng nhau. (Khi t\u00ednh to\u00e1n n\u00ean c\u00e2n nh\u1eafc c\u00f3 n\u00ean r\u00fat g\u1ecdn ph\u00e2n s\u1ed1 hay kh\u00f4ng.) 8 + Chi\u1ec1u d\u00e0i h\u00ecnh ch\u1eef nh\u1eadt t\u00f4 m\u00e0u g\u1ed3m 8 ph\u1ea7n \u2192 10 m. Chi\u1ec1u r\u1ed9ng h\u00ecnh ch\u1eef nh\u1eadt t\u00f4 m\u00e0u g\u1ed3m 7 ph\u1ea7n \u2192 7 m. 10 295","Di\u1ec7n t\u00edch h\u00ecnh ch\u1eef nh\u1eadt t\u00f4 m\u00e0u l\u00e0: 8 \u00d7 7 = 56 (m2). 10 10 100 4 + C\u1ea1nh h\u00ecnh vu\u00f4ng m\u00e0u xanh g\u1ed3m 4 ph\u1ea7n \u2192 10 m. Di\u1ec7n t\u00edch h\u00ecnh vu\u00f4ng m\u00e0u xanh l\u00e0: 4 \u00d7 4 = 16 (m2). 10 10 100 + Di\u1ec7n t\u00edch ph\u1ea7n m\u00e0u v\u00e0ng l\u00e0: 56 \u2212 16 = 40 (m2) hay 2 m2. 100 100 100 5 C\u00e1ch 2: H\u00ecnh vu\u00f4ng c\u1ea1nh 1 m c\u00f3 di\u1ec7n t\u00edch 1 m2. H\u00ecnh vu\u00f4ng n\u00e0y \u0111\u01b0\u1ee3c chia th\u00e0nh 100 \u00f4 vu\u00f4ng nh\u1ecf b\u1eb1ng nhau. 2 40 5 Ph\u1ea7n t\u00f4 m\u00e0u v\u00e0ng g\u1ed3m 40 \u00f4 vu\u00f4ng n\u00ean c\u00f3 di\u1ec7n t\u00edch l\u00e0 100 m2 hay m2. \u2022 B\u01b0\u1edbc 4: Ki\u1ec3m tra l\u1ea1i \u0110\u1ebfm s\u1ed1 \u00f4 vu\u00f4ng c\u00f3 \u0111\u00fang kh\u00f4ng? Vi\u1ec7c t\u00ednh to\u00e1n c\u00f3 \u0111\u00fang kh\u00f4ng? \u2013 GV h\u1ec7 th\u1ed1ng l\u1ea1i vi\u1ec7c l\u00e0m c\u1ee7a c\u00e1c nh\u00f3m. B\u00e0i 75. PH\u00c9P CHIA PH\u00c2N S\u1ed0 (2 ti\u1ebft) A. Y\u00eau c\u1ea7u c\u1ea7n \u0111\u1ea1t \u2013 HS nh\u1eadn bi\u1ebft \u0111\u01b0\u1ee3c c\u00e1ch chia hai ph\u00e2n s\u1ed1; th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c ph\u00e9p chia hai ph\u00e2n s\u1ed1. \u2013 V\u1eadn d\u1ee5ng gi\u1ea3i quy\u1ebft c\u00e1c v\u1ea5n \u0111\u1ec1 \u0111\u01a1n gi\u1ea3n li\u00ean quan \u0111\u1ebfn ph\u00e9p nh\u00e2n, ph\u00e9p chia c\u00e1c ph\u00e2n s\u1ed1. \u2013 HS c\u00f3 c\u01a1 h\u1ed9i \u0111\u1ec3 ph\u00e1t tri\u1ec3n c\u00e1c n\u0103ng l\u1ef1c t\u01b0 duy v\u00e0 l\u1eadp lu\u1eadn to\u00e1n h\u1ecdc; giao ti\u1ebfp to\u00e1n h\u1ecdc; m\u00f4 hi\u0300nh ho\u00e1 toa\u0301n ho\u0323c; s\u1eed d\u1ee5ng c\u00f4ng c\u1ee5, ph\u01b0\u01a1ng ti\u1ec7n h\u1ecdc to\u00e1n; gi\u1ea3i quy\u1ebft v\u1ea5n \u0111\u1ec1 to\u00e1n h\u1ecdc v\u00e0 c\u00e1c ph\u1ea9m ch\u1ea5t nh\u00e2n \u00e1i, tr\u00e1ch nhi\u1ec7m. B. \u0110\u1ed3 d\u00f9ng d\u1ea1y h\u1ecdc GV: C\u00e1c h\u00ecnh \u1ea3nh c\u00f3 trong b\u00e0i (n\u1ebfu c\u1ea7n). HS: Gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng. C. C\u00e1c ho\u1ea1t \u0111\u1ed9ng d\u1ea1y h\u1ecdc ch\u1ee7 y\u1ebfu I. Kh\u1edfi \u0111\u1ed9ng T\u1ed5 ch\u1ee9c cho HS ho\u1ea1t \u0111\u1ed9ng nh\u00f3m. C\u00e1c nh\u00f3m th\u1ef1c hi\u1ec7n theo c\u00e1c y\u00eau c\u1ea7u sau: \u2013 \u0110\u1ecdc c\u00e1c th\u00f4ng tin trong ph\u1ea7n kh\u1edfi \u0111\u1ed9ng. 3 : 1 ) \u2013 Vi\u1ebft ph\u00e9p t\u00ednh t\u00ecm chi\u1ec1u d\u00e0i m\u1ea3nh gi\u1ea5y. ( 4 2 296","\u2013 D\u00f9ng gi\u1ea5y k\u1ebb \u00f4 vu\u00f4ng, th\u1ef1c hi\u1ec7n vi\u1ec7c t\u00ecm di\u1ec7n t\u00edch: C\u1ea7n v\u1ebd ho\u1eb7c tr\u00ecnh chi\u1ebfu h\u00ecnh vu\u00f4ng c\u00f3 di\u1ec7n t\u00edch \u0111\u01b0\u1ee3c th\u1ec3 hi\u1ec7n l\u00e0 1 m2 (nh\u01b0 SGK). \u0110\u1ebfm theo c\u1ea1nh m\u1ed7i h\u00ecnh vu\u00f4ng l\u00e0 10 \u00f4 vu\u00f4ng. 1m X\u00e1c \u0111\u1ecbnh chi\u1ec1u r\u1ed9ng m\u1ea3nh gi\u1ea5y. T\u00f4 m\u00e0u ph\u1ea7n bi\u1ec3u th\u1ecb 3 m2. 4 1m D\u1ef1a v\u00e0o h\u00ecnh v\u1ebd, t\u00ecm chi\u1ec1u d\u00e0i m\u1ea3nh gi\u1ea5y. \u2013 Th\u00f4ng b\u00e1o k\u1ebft qu\u1ea3 v\u00e0 gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. \u2013 GV \u0111\u01b0a h\u00ecnh \u1ea3nh l\u00ean b\u1ea3ng. 1m 1m 1 m 2 N\u1ebfu c\u1ea1nh h\u00ecnh vu\u00f4ng l\u1edbn l\u00e0 1 m \u0111\u01b0\u1ee3c chia th\u00e0nh 2 ph\u1ea7n b\u1eb1ng nhau th\u00ec m\u1ed7i ph\u1ea7n l\u00e0 1 m 2 \u2192 Chi\u1ec1u d\u00e0i m\u1ea3nh gi\u1ea5y g\u1ed3m 3 ph\u1ea7n nh\u01b0 th\u1ebf 1 3 \u2192 Chi\u1ec1u d\u00e0i m\u1ea3nh gi\u1ea5y l\u00e0 2 m\u00d73= 2 m \u2192 3 : 1 = 3 . 4 2 2 \u2013 GV \u0111\u1eb7t v\u1ea5n \u0111\u1ec1: Ta \u0111\u00e3 d\u1ef1a v\u00e0o h\u00ecnh v\u1ebd \u0111\u1ec3 t\u00ednh chi\u1ec1u d\u00e0i h\u00ecnh ch\u1eef nh\u1eadt. N\u1ebfu kh\u00f4ng c\u00f3 h\u00ecnh v\u1ebd th\u00ec th\u1ef1c hi\u1ec7n c\u00e1ch n\u00e0o? \u2192 Gi\u1edbi thi\u1ec7u b\u00e0i m\u1edbi. II. Kh\u00e1m ph\u00e1, h\u00ecnh th\u00e0nh ki\u1ebfn th\u1ee9c m\u1edbi: Ph\u00e9p chia ph\u00e2n s\u1ed1 1. V\u00ed d\u1ee5 1 \u2013 GV vi\u1ebft b\u1ea3ng: \t 3 : 1 = 3 \u00d7 2 4 2 4 1 3 2 3\u00d72 3 \u2013 HS th\u1ef1c hi\u1ec7n ph\u00e9p nh\u00e2n 4 \u00d7 1 = 4\u00d71 = 2 \u2013 So s\u00e1nh v\u1edbi k\u1ebft qu\u1ea3 \u0111\u00e3 th\u1ef1c hi\u1ec7n \u1edf ph\u1ea7n Kh\u1edfi \u0111\u1ed9ng. \u2013 GV vi\u1ebft ti\u1ebfp: 3 1 3 2 3 4 2 4 1 2 \t\t : = \u00d7 = \u2013 GV n\u00f3i v\u00e0 vi\u1ebft: \u0110\u1ec3 th\u1ef1c hi\u1ec7n ph\u00e9p chia hai ph\u00e2n s\u1ed1, ta l\u1ea5y ph\u00e2n s\u1ed1 th\u1ee9 nh\u1ea5t nh\u00e2n v\u1edbi ph\u00e2n s\u1ed1 th\u1ee9 hai \u0111\u1ea3o ng\u01b0\u1ee3c. 2 1 \u2013 GV gi\u1ea3i th\u00edch: 1 l\u00e0 ph\u00e2n s\u1ed1 \u0111\u1ea3o ng\u01b0\u1ee3c c\u1ee7a ph\u00e2n s\u1ed1 2 . 297","2. V\u00ed d\u1ee5 2 \u2013 HS (nh\u00f3m b\u1ed1n) th\u1ea3o lu\u1eadn, t\u00ecm c\u00e1ch th\u1ef1c hi\u1ec7n. \u2013 GV c\u00f3 th\u1ec3 g\u1ee3i \u00fd: Ta n\u00ean r\u00fat g\u1ecdn \u1edf b\u01b0\u1edbc th\u1ee9 hai. \u2013 HS th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n r\u1ed3i chia s\u1ebb v\u1edbi b\u1ea1n trong nh\u00f3m. \u2013 S\u1eeda b\u00e0i, HS tr\u00ecnh b\u00e0y tr\u00ean b\u1ea3ng l\u1edbp, gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. 5 5 5 6 1 \t\t\t 18 : 6 = 18 \u00d7 5 = 3 V\u00ed d\u1ee5: R\u00fat g\u1ecdn 5 v\u00e0 5 cho 5, 6 v\u00e0 18 cho 6 \u2192 5 : 5 = 1 v\u00e0 18 : 6 = 3 \t\t \u2192 5 \u00d7 6 = 51 \u00d7 6 1 = 1 18 5 183 \u00d7 51 3 III. Th\u1ef1c h\u00e0nh, luy\u1ec7n t\u1eadp 1. Th\u1ef1c h\u00e0nh Ba\u0300i 1: \u2013 T\u00ecm hi\u1ec3u m\u1eabu \u2192 L\u1ea5y ph\u00e2n s\u1ed1 th\u1ee9 nh\u1ea5t nh\u00e2n v\u1edbi ph\u00e2n s\u1ed1 th\u1ee9 hai \u0111\u1ea3o ng\u01b0\u1ee3c. \u2013 C\u00f3 th\u1ec3 d\u00f9ng h\u00ecnh th\u1ee9c \u201cH\u1ecfi nhanh, \u0111\u00e1p g\u1ecdn\u201d, gi\u00fap HS th\u1ef1c hi\u1ec7n \u0111\u01b0\u1ee3c vi\u1ec7c n\u00eau ph\u00e2n s\u1ed1 \u0111\u1ea3o ng\u01b0\u1ee3c c\u1ee7a c\u00e1c s\u1ed1: 4 6 \t\t 9 ; 5 ; 3. \u2013 HS (nh\u00f3m \u0111\u00f4i) nh\u1eadn bi\u1ebft y\u00eau c\u1ea7u c\u1ee7a b\u00e0i, th\u1ef1c hi\u1ec7n c\u00e1 nh\u00e2n (b\u1ea3ng con). \u2013 B\u00e0i n\u00e0y ch\u1ec9 y\u00eau c\u1ea7u HS chuy\u1ec3n ph\u00e9p chia c\u00e1c ph\u00e2n s\u1ed1 th\u00e0nh ph\u00e9p nh\u00e2n, ch\u01b0a y\u00eau c\u1ea7u t\u00ednh k\u1ebft qu\u1ea3. \u2013 S\u1eeda b\u00e0i, GV khuy\u1ebfn kh\u00edch HS tr\u00ecnh b\u00e0y c\u00e1ch l\u00e0m. V\u00ed d\u1ee5: 4 9 9 4 2 9 2 4 4 9 a) 7 : = 7 \u00d7 (v\u00ec l\u00e0 ph\u00e2n s\u1ed1 \u0111\u1ea3o ng\u01b0\u1ee3c c\u1ee7a ph\u00e2n s\u1ed1 ). \u2026 Ba\u0300i 2: \u2013 Tr\u01b0\u1edbc khi l\u00e0m b\u00e0i, l\u01b0u \u00fd HS: + Chuy\u1ec3n v\u1ec1 ph\u00e9p nh\u00e2n: L\u01b0u \u00fd ch\u1ec9 chuy\u1ec3n ph\u00e2n s\u1ed1 th\u1ee9 hai th\u00e0nh ph\u00e2n s\u1ed1 \u0111\u1ea3o ng\u01b0\u1ee3c. + N\u00ean th\u1ef1c hi\u1ec7n vi\u1ec7c r\u00fat g\u1ecdn tr\u01b0\u1edbc khi t\u00ecm t\u00edch. \u2013 S\u1eeda b\u00e0i: C\u00f3 th\u1ec3 d\u00f9ng h\u00ecnh th\u1ee9c thi \u0111ua, khuy\u1ebfn kh\u00edch c\u00e1c em n\u00f3i. V\u00ed d\u1ee5: c) 4 : 8 = 4 \u00d7 3 \t (chuy\u1ec3n v\u1ec1 ph\u00e9p nh\u00e2n) 15 3 15 8 41 \u00d7 31 = 155 \u00d7 82 (r\u00fat g\u1ecdn 3 v\u00e0 15 cho 3, 4 v\u00e0 8 cho 4) = 1 10 298","2. Luy\u1ec7n t\u1eadp B\u00e0i 1: \u2013 HS (nh\u00f3m \u0111\u00f4i) nh\u1eadn bi\u1ebft y\u00eau c\u1ea7u, th\u1ea3o lu\u1eadn c\u00e1ch tr\u00ecnh b\u00e0y: Vi\u1ebft ph\u00e9p chia c\u1ea7n t\u00ednh \u2192 Chuy\u1ec3n sang ph\u00e9p nh\u00e2n \u2192 t\u1eed \u00d7 t\u1eed m\u1eabu \u00d7 m\u1eabu \u2192 R\u00fat g\u1ecdn \u2192 Vi\u1ebft k\u1ebft qu\u1ea3. \u2013 HS l\u00e0m c\u00e1 nh\u00e2n, s\u1eeda b\u00e0i theo nh\u00f3m. IV. V\u1eadn d\u1ee5ng, tr\u1ea3i nghi\u1ec7m B\u00e0i 2: \u2013 HS (nh\u00f3m b\u1ed1n) nh\u1eadn bi\u1ebft y\u00eau c\u1ea7u, th\u1ea3o lu\u1eadn c\u00e1ch tr\u00ecnh b\u00e0y: T\u00ednh (Di\u1ec7n t\u00edch, Chu vi, Chi\u1ec1u d\u00e0i, Chi\u1ec1u r\u1ed9ng h\u00ecnh ch\u1eef nh\u1eadt) \u2192 Nh\u1eafc l\u1ea1i quy t\u1eafc t\u00ecm di\u1ec7n t\u00edch, chu vi h\u00ecnh ch\u1eef nh\u1eadt \u2192 C\u00e2u th\u1ee9 nh\u1ea5t: Bi\u1ebft Chi\u1ec1u d\u00e0i, Chi\u1ec1u r\u1ed9ng, \u00e1p d\u1ee5ng quy t\u1eafc, t\u00ecm Di\u1ec7n t\u00edch, Chu vi. C\u00e2u th\u1ee9 hai: Bi\u1ebft Chi\u1ec1u d\u00e0i v\u00e0 Di\u1ec7n t\u00edch \u2192 T\u00ecm \u0111\u01b0\u1ee3c g\u00ec? (Chi\u1ec1u r\u1ed9ng) C\u00f3 Chi\u1ec1u d\u00e0i v\u00e0 Chi\u1ec1u r\u1ed9ng \u2192 T\u00ecm Chu vi. \u2013 HS l\u00e0m b\u00e0i c\u00e1 nh\u00e2n. \u2013 S\u1eeda b\u00e0i: C\u00e1c nh\u00f3m thi \u0111ua, HS tr\u00ecnh b\u00e0y c\u00e1ch l\u00e0m. Vui h\u1ecdc 1 : 1 3 0 : 15 0 5 : 5 2 3 2 14 7 7 \u2013 Ho\u1ea1t \u0111\u1ed9ng theo nh\u00f3m. Nh\u1eadn bi\u1ebft vi\u1ec7c c\u1ea7n l\u00e0m: Theo b\u00f3ng n\u00f3i 2 4 1 c\u1ee7a ong. 3 15 Th\u1ef1c hi\u1ec7n c\u00e1c ph\u00e9p t\u00ednh v\u00e0 t\u00ecm \u0111\u01b0\u1eddng \u0111i. \u2013 Nh\u00f3m n\u00e0o l\u00e0m \u0111\u00fang v\u00e0 xong tr\u01b0\u1edbc th\u00ec th\u1eafng cu\u1ed9c. 4 \u00d72 8 \u0110\u00edch 6 3 \u00d7 3 Gi\u1ea3i th\u00edch t\u1ea1i sao \u0111i theo \u0111\u01b0\u1eddng nh\u01b0 v\u1eady. 5 5 4 2 2 259 584 4 :2 8 1: 5 1 6 \u00d7 11 5 5 8 11 6 Kh\u00e1m ph\u00e1 \u2013 HS (nh\u00f3m \u0111\u00f4i) \u0111\u1ecdc k\u0129 v\u0103n b\u1ea3n, GV gi\u00fap c\u00e1c em hi\u1ec3u v\u1ec1 t\u1ea5m v\u1ea3i, kh\u1ed5 v\u1ea3i: N\u1ebfu tr\u1ea3i t\u1ea5m v\u1ea3i ra, ta \u0111\u01b0\u1ee3c m\u1ed9t h\u00ecnh ch\u1eef nh\u1eadt r\u1ea5t d\u00e0i m\u00e0 chi\u1ec1u r\u1ed9ng t\u1ea5m v\u1ea3i g\u1ecdi l\u00e0 kh\u1ed5 v\u1ea3i. \u2013 GV v\u1ebd h\u00ecnh minh ho\u1ea1 c\u00e1c th\u00f4ng tin c\u1ea7n thi\u1ebft \u0111\u1ec3 HS l\u00e0m b\u00e0i. 8 m 5 90 cm 1 \u00e1o 8m Chuy\u1ec3n v\u1ec1 b\u00e0i to\u00e1n: 8 m. H\u1ecfi \u0111\u01b0\u1ee3c bao nhi\u00eau m\u1ea3nh v\u1ea3i nh\u01b0 v\u1eady? (8 : 8 = 5) C\u1eaft \u0111\u1ec1u 8 m v\u1ea3i th\u00e0nh c\u00e1c m\u1ea3nh v\u1ea3i d\u00e0i 5 5 \u2013 S\u1eeda b\u00e0i, HS gi\u1ea3i th\u00edch c\u00e1ch l\u00e0m. 299"]