{"segment":[{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":" <span class='basic_left'>Cho bi\u1ebft t t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi z theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 a, z t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi y theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 b, y t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi x theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 c ( a, b, c l\u00e0 c\u00e1c h\u1eb1ng s\u1ed1 kh\u00e1c 0). t t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi x theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0? <\/span>","select":["A. a + b + c ","B. abc","C. a - b - c ","D. a : b : c "],"explain":"<span class='basic_left'> Ta c\u00f3: t t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi z theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 a n\u00ean t = az (1)<br\/> z t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi y theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 b n\u00ean z = by (2) <br\/> y t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi x theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 c n\u00ean y = cx (3) <br\/> T\u1eeb (1), (2) v\u00e0 (3) ta c\u00f3: t = a.(by) = ab.(cx) = abc.x <br\/> Suy ra t t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi x theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 abc. <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":601},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["75"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" <span class='basic_left'>V\u1edbi s\u1ed1 ti\u1ec1n \u0111\u1ec3 mua 60 m v\u1ea3i lo\u1ea1i I c\u00f3 th\u1ec3 mua \u0111\u01b0\u1ee3c bao nhi\u00eau m\u00e9t v\u1ea3i lo\u1ea1i II? Bi\u1ebft r\u1eb1ng gi\u00e1 ti\u1ec1n v\u1ea3i lo\u1ea1i II b\u1eb1ng 80% gi\u00e1 ti\u1ec1n v\u1ea3i lo\u1ea1i I. <br\/> \u0110\u00e1p s\u1ed1: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (m)$ <\/span> ","explain":"<span class='basic_left'> G\u1ecdi $x$ (m) l\u00e0 s\u1ed1 m\u00e9t v\u1ea3i lo\u1ea1i II mua \u0111\u01b0\u1ee3c v\u1edbi s\u1ed1 ti\u1ec1n \u0111\u1ec3 mua 60m v\u1ea3i lo\u1ea1i I, ta c\u00f3: <br\/> $ \\dfrac{x}{60} = \\dfrac{\\text{gi\u00e1 1m v\u1ea3i lo\u1ea1i I}}{\\text{gi\u00e1 1m v\u1ea3i lo\u1ea1i II}} = \\dfrac{100}{80} = \\dfrac{5}{4} $ <br\/> Suy ra $ x = \\dfrac{60.5}{4} = 75 $ <br\/> V\u1eady v\u1edbi c\u00f9ng s\u1ed1 ti\u1ec1n mua 60m v\u1ea3i lo\u1ea1i I th\u00ec mua \u0111\u01b0\u1ee3c 75m v\u1ea3i lo\u1ea1i II. <br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 75. <\/span><\/span> "}]}],"id_ques":602},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["450"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" <span class='basic_left'> Hai \u00f4 t\u00f4 kh\u1edfi h\u00e0nh c\u00f9ng m\u1ed9t l\u00fac t\u1eeb hai \u0111\u1ecba \u0111i\u1ec3m A v\u00e0 B, \u0111i ng\u01b0\u1ee3c chi\u1ec1u nhau. Khi g\u1eb7p nhau \u00f4 t\u00f4 t\u1eeb B \u0111i \u0111\u01b0\u1ee3c qu\u00e3ng \u0111\u01b0\u1eddng d\u00e0i h\u01a1n qu\u00e3ng \u0111\u01b0\u1eddng \u00f4 t\u00f4 \u0111i t\u1eeb A l\u00e0 50 km. T\u00ednh qu\u00e3ng \u0111\u01b0\u1eddng AB, bi\u1ebft v\u1eadn t\u1ed1c c\u1ee7a \u00f4 t\u00f4 \u0111i t\u1eeb A v\u00e0 B t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi 4 v\u00e0 5? <br\/> \u0110\u00e1p s\u1ed1: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (km)$ <\/span> ","hint":"L\u1ea5y t\u1ec9 l\u1ec7 v\u1ec1 qu\u00e3ng \u0111\u01b0\u1eddng v\u00e0 v\u1eadn t\u1ed1c. ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1: X\u00e1c \u0111\u1ecbnh quan h\u1ec7 t\u1ec9 l\u1ec7 thu\u1eadn gi\u1eefa hai \u0111\u1ea1i l\u01b0\u1ee3ng $y$ v\u00e0 $x$. <br\/>B\u01b0\u1edbc 2: \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t t\u1ec9 s\u1ed1 hai gi\u00e1 tr\u1ecb b\u1ea5t k\u00ec c\u1ee7a \u0111\u1ea1i l\u01b0\u1ee3ng n\u00e0y b\u1eb1ng t\u1ec9 s\u1ed1 hai gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a \u0111\u1ea1i l\u01b0\u1ee3ng kia. <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> G\u1ecdi qu\u00e3ng \u0111\u01b0\u1eddng \u00f4 t\u00f4 xu\u1ea5t ph\u00e1t t\u1eeb A \u0111\u1ebfn ch\u1ed7 g\u1eb7p nhau l\u00e0 $S_{1}$, v\u1edbi v\u1eadn t\u1ed1c l\u00e0 $v_{1}$. <br\/> Qu\u00e3ng \u0111\u01b0\u1eddng \u00f4 t\u00f4 xu\u1ea5t ph\u00e1t t\u1eeb B \u0111\u1ec5n ch\u1ed7 g\u1eb7p nhau l\u00e0 $S_{2}$, v\u1edbi v\u1eadn t\u1ed1c l\u00e0 $v_{2}$. <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $S_{2} - S_{1} = 50$ v\u00e0 $ \\dfrac{v_{1}}{4} = \\dfrac{v_{2}}{5} \\Rightarrow \\dfrac{v_{1}}{v_{2}} = \\dfrac{4}{5} $ <br\/> V\u1edbi c\u00f9ng m\u1ed9t th\u1eddi gian th\u00ec qu\u00e3ng \u0111\u01b0\u1eddng v\u00e0 v\u1eadn t\u1ed1c l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn, n\u00ean ta c\u00f3: <br\/> $ \\dfrac{S_{1}}{S_{2}} = \\dfrac{v_{1}}{v_{2}} = \\dfrac{4}{5} $ <br\/> Do \u0111\u00f3 $\\dfrac{S_{1}}{4} = \\dfrac{S_{2}}{5} = \\dfrac{S_{2}-S_{1}}{5-4} = \\dfrac{50}{1} = 50 $ <br\/> V\u1eady $S_{1} = 50.4 = 200 \\\\ S_{2} = 50.5 = 250$ <br\/> Qu\u00e3ng \u0111\u01b0\u1eddng AB d\u00e0i l\u00e0 : 200 + 250 = 450 (km).<br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 450. <\/span><\/span> "}]}],"id_ques":603},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":10,"ques":" <span class='basic_left'> Hai h\u00ecnh ch\u1eef nh\u1eadt c\u00f3 c\u00f9ng chi\u1ec1u d\u00e0i. Chi\u1ec1u r\u1ed9ng c\u1ee7a ch\u00fang l\u1ea7n l\u01b0\u1ee3t t\u1ec9 l\u1ec7 v\u1edbi 3 v\u00e0 4. Hi\u1ec7u di\u1ec7n t\u00edch c\u1ee7a ch\u00fang l\u00e0 7 cm$^{2}$. T\u00ednh di\u1ec7n t\u00edch c\u1ee7a m\u1ed7i h\u00ecnh ch\u1eef nh\u1eadt \u0111\u00f3? <\/span>","select":["A. 28 cm$^{2}$ v\u00e0 21 cm$^{2}$ ","B. 14 cm$^{2}$ v\u00e0 7 cm$^{2}$ ","C. 6 cm$^{2}$ v\u00e0 13 cm$^{2}$","D. 9 cm$^{2}$ v\u00e0 16 cm$^{2}$"],"hint":"D\u1ef1a v\u00e0o c\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh ch\u1eef nh\u1eadt suy ra di\u1ec7n t\u00edch c\u1ee7a hai h\u00ecnh ch\u1eef nh\u1eadt \u0111\u00f3 t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi chi\u1ec1u r\u1ed9ng c\u1ee7a ch\u00fang. ","explain":" <span class='basic_left'> G\u1ecdi di\u1ec7n t\u00edch c\u1ee7a hai h\u00ecnh ch\u1eef nh\u1eadt l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y$ (cm$^{2}$). <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $x - y = 7 $ <br\/> Vi hai h\u00ecnh ch\u1eef nh\u1eadt c\u00f3 c\u00f9ng chi\u1ec1u d\u00e0i, n\u00ean chi\u1ec1u r\u1ed9ng c\u1ee7a h\u00ecnh ch\u1eef nh\u1eadt v\u00e0 di\u1ec7n t\u00edch l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn . <br\/> Suy ra ta c\u00f3: $ \\dfrac{x}{4} = \\dfrac{y}{3} = \\dfrac{x-y}{4-3} = \\dfrac{7}{1} = 7 \\\\ \\Rightarrow x = 7.4 = 28 \\\\ y = 7.3 = 21 $ <br\/> V\u1eady di\u1ec7n t\u00edch hai h\u00ecnh ch\u1eef nh\u1eadt l\u1ea7n l\u01b0\u1ee3t l\u00e0 28 cm$^{2}$ v\u00e0 21 cm$^{2}$.<br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":2}]}],"id_ques":604},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":10,"ques":" <span class='basic_left'> Trong m\u1ed9t bu\u1ed5i lao \u0111\u1ed9ng tr\u1ed3ng c\u00e2y, ba l\u1edbp 7A, 7B, 7C c\u00f3 t\u1ea5t c\u1ea3 105 h\u1ecdc sinh tham gia . S\u1ed1 c\u00e2y tr\u1ed3ng \u0111\u01b0\u1ee3c c\u1ee7a l\u1edbp 7A v\u00e0 7B t\u1ec9 l\u1ec7 v\u1edbi 2 v\u00e0 3. S\u1ed1 c\u00e2y tr\u1ed3ng \u0111\u01b0\u1ee3c c\u1ee7a 7B v\u00e0 7C t\u1ec9 l\u1ec7 v\u1edbi 4 v\u00e0 5. H\u1ecfi m\u1ed7i l\u1edbp c\u00f3 bao nhi\u00eau h\u1ecdc sinh tham gia tr\u1ed3ng c\u00e2y? (bi\u1ebft m\u1ed7i h\u1ecdc sinh \u0111\u1ec1u tr\u1ed3ng m\u1ed9t s\u1ed1 c\u00e2y nh\u01b0 nhau) <\/span>","select":["A. 32, 28, 45 h\u1ecdc sinh ","B. 24, 30, 45 h\u1ecdc sinh ","C. 24, 32, 44 h\u1ecdc sinh ","D. 24, 36, 45 h\u1ecdc sinh "],"hint":"S\u1ed1 h\u1ecdc sinh tham gia tr\u1ed3ng c\u00e2y v\u00e0 s\u1ed1 c\u00e2y tr\u1ed3ng \u0111\u01b0\u1ee3c l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn. ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1: L\u1eadp d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau. <br\/>B\u01b0\u1edbc 2: V\u1eadn d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau \u0111\u1ec3 gi\u1ea3i. <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> G\u1ecdi s\u1ed1 h\u1ecdc sinh tham gia tr\u1ed3ng c\u00e2y c\u1ee7a 3 l\u1edbp 7A, 7B, 7C l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y, z$ (h\u1ecdc sinh). <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3 $x + y + z = 105$ <br\/> V\u00ec s\u1ed1 h\u1ecdc sinh tham gia tr\u1ed3ng c\u00e2y v\u00e0 s\u1ed1 c\u00e2y tr\u1ed3ng \u0111\u01b0\u1ee3c l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn. <br\/> M\u00e0 s\u1ed1 c\u00e2y tr\u1ed3ng \u0111\u01b0\u1ee3c c\u1ee7a l\u1edbp 7A v\u00e0 7B t\u1ec9 l\u1ec7 v\u1edbi 2 v\u00e0 3, s\u1ed1 c\u00e2y tr\u1ed3ng \u0111\u01b0\u1ee3c c\u1ee7a 7B v\u00e0 7C t\u1ec9 l\u1ec7 v\u1edbi 4 v\u00e0 5. <br\/> Do \u0111\u00f3 $ \\dfrac{x}{2} = \\dfrac{y}{3} $ v\u00e0 $ \\dfrac{y}{4} = \\dfrac{z}{5} \\Rightarrow \\dfrac{x}{8} = \\dfrac{y}{12} $ v\u00e0 $\\dfrac{y}{12} = \\dfrac{z}{15}$ <br\/> $\\Rightarrow \\dfrac{x}{8} = \\dfrac{y}{12} = \\dfrac{z}{15} = \\dfrac{x+y+z}{8+12+15} = \\dfrac{105}{35} = 3 \\\\ \\Rightarrow x = 8.3 = 24 \\\\ y = 12 .3 = 36 \\\\ z = 15 .3 = 45 $ <br\/> V\u1eady s\u1ed1 h\u1ecdc sinh tham gia tr\u1ed3ng c\u00e2y c\u1ee7a m\u1ed7i l\u1edbp l\u1ea7n l\u01b0\u1ee3t l\u00e0: 24, 36, 45 h\u1ecdc sinh.<br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span><\/span> ","column":2}]}],"id_ques":605},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":" <span class='basic_left'> T\u1ed5ng s\u1ed1 ti\u1ec1n l\u01b0\u01a1ng c\u1ee7a ba b\u00e1c c\u00f4ng nh\u00e2n A, B, C l\u00e0 1 350 000 \u0111\u1ed3ng. \u0110\u1ee3t 1, m\u1ed7i b\u00e1c \u0111\u00e3 l\u0129nh 200 000 \u0111\u1ed3ng. \u0110\u1ee3t 2, s\u1ed1 ti\u1ec1n ba b\u00e1c A, B, C l\u0129nh \u0111\u01b0\u1ee3c t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi 2; 2,5 v\u00e0 3. H\u1ecfi c\u1ea3 hai \u0111\u1ee3t, m\u1ed7i b\u00e1c \u0111\u01b0\u1ee3c l\u0129nh bao nhi\u00eau ti\u1ec1n l\u01b0\u01a1ng? <\/span>","select":["A. 450 000 \u0111\u1ed3ng, 450 000 \u0111\u1ed3ng, 450 000 \u0111\u1ed3ng ","B. 400 000 \u0111\u1ed3ng, 450 000 \u0111\u1ed3ng, 500 000 \u0111\u1ed3ng ","C. 400 000 \u0111\u1ed3ng, 400 000 \u0111\u1ed3ng, 550 000 \u0111\u1ed3ng ","D. 450 000 \u0111\u1ed3ng, 450 000 \u0111\u1ed3ng, 500 000 \u0111\u1ed3ng "],"explain":"<span class='basic_left'> G\u1ecdi s\u1ed1 ti\u1ec1n l\u01b0\u01a1ng c\u1ee7a ba b\u00e1c c\u00f4ng nh\u00e2n A, B, C l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y, z (0< x, y, z < 1 350 000)$. <br\/> Ta c\u00f3: $x + y + z = 1350000$ <br\/> Sau \u0111\u1ee3t 1, m\u1ed7i b\u00e1c c\u00f2n s\u1ed1 ti\u1ec1n l\u00e0: $ x - 200000; y - 200000; z - 200000$ <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $ \\dfrac{x-200000}{2} = \\dfrac{y-200000}{2,5} = \\dfrac{z-200000}{3} \\\\ = \\dfrac{x+y+z-600000}{2+2,5+3} \\\\ = \\dfrac{1350000-600000}{7,5} = \\dfrac{750000}{7,5} = 100000 $ <br\/> Suy ra: $ \\dfrac{x-200000}{2} = 100000 \\Rightarrow x = 400 000 \\\\ \\dfrac{y-200000}{2,5} = 100000 \\Rightarrow y = 450 000 \\\\ \\dfrac{z-200000}{3} = 100000 \\Rightarrow z = 500 000 $ <br\/> V\u1eady c\u1ea3 hai \u0111\u1ee3t m\u1ed7i b\u00e1c l\u1ea7n l\u01b0\u1ee3t l\u0129nh \u0111\u01b0\u1ee3c: 400 000 \u0111\u1ed3ng, 450 000 \u0111\u1ed3ng, 500 000 \u0111\u1ed3ng. <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":606},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["12"],["30"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" <span class='basic_left'> M\u1ed9t ng\u01b0\u1eddi \u0111i xe \u0111\u1ea1p v\u00e0 m\u1ed9t ng\u01b0\u1eddi \u0111i xe m\u00e1y c\u00f9ng \u0111i m\u1ed9t l\u00fac t\u1eeb A t\u1edbi B. V\u00ec v\u1eadn t\u1ed1c xe \u0111\u1ea1p nh\u1ecf h\u01a1n v\u1eadn t\u1ed1c xe m\u00e1y l\u00e0 18 km\/h n\u00ean khi xe \u0111\u1ea1p t\u1edbi C th\u00ec xe m\u00e1y \u0111\u00e3 t\u1edbi D qu\u00e1 C m\u1ed9t qu\u00e3ng \u0111\u01b0\u1eddng b\u1eb1ng 0,6 qu\u00e3ng \u0111\u01b0\u1eddng AD. T\u00ednh v\u1eadn t\u1ed1c m\u1ed7i xe? <br\/> \u0110\u00e1p s\u1ed1: V\u1eadn t\u1ed1c xe \u0111\u1ea1p = $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (km\/h) $ <br\/> $\\hspace{1,8cm} $ V\u1eadn t\u1ed1c xe m\u00e1y = $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (km\/h)$<\/span> ","explain":"<span class='basic_left'> K\u00ed hi\u1ec7u qu\u00e3ng \u0111\u01b0\u1eddng $S_{1} = AC $ v\u00e0 $S_{2} = AD $, <br\/> ta c\u00f3: $ \\dfrac{CD}{AD} = 0,6 = \\dfrac{3}{5}, $ do \u0111\u00f3 $ \\dfrac{S_{1}}{S_{2}} = \\dfrac{AC}{AD} = \\dfrac{2}{5}$ <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/daiso/bai13/lv3/img\/D7C21-K1-01.png'\/><\/center> G\u1ecdi v\u1eadn t\u1ed1c xe \u0111\u1ea1p \u0111i t\u1eeb A t\u1edbi C l\u00e0 $v_{1},$ v\u1eadn t\u1ed1c xe m\u00e1y \u0111i t\u1eeb A t\u1edbi D l\u00e0 $v_{2}$ <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $v_{2} - v_{1} = 18$ (km\/h) <br\/> Hai xe kh\u1edfi h\u00e0nh c\u00f9ng m\u1ed9t l\u00fac t\u1eeb A, m\u1ed9t xe t\u1edbi C v\u00e0 m\u1ed9t xe t\u1edbi D n\u00ean c\u00f9ng th\u1eddi gian th\u00ec qu\u00e3ng \u0111\u01b0\u1eddng \u0111i \u0111\u01b0\u1ee3c v\u00e0 v\u1eadn t\u1ed1c l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn. <br\/> Ta c\u00f3: $\\dfrac{v_{1}}{v_{2}} = \\dfrac{S_{1}}{S_{2}} = \\dfrac{2}{5} $ <br\/> Suy ra $\\dfrac{v_{1}}{2} = \\dfrac{v_{2}}{5} = \\dfrac{v_{2}-v_{1}}{5-2} = \\dfrac{18}{3} = 6 $ <br\/> V\u1eady v\u1eadn t\u1ed1c xe \u0111\u1ea1p: $v_{1} = 6.2 = 12 $ (km\/h) <br\/> V\u1eadn t\u1ed1c xe m\u00e1y: $v_{2} = 6.5 = 30 $ (km\/h) <br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 12; 30. <\/span><\/span> "}]}],"id_ques":607},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["432"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" <span class='basic_left'> C\u00f3 hai \u0111\u1ed9i c\u00f4ng nh\u00e2n. \u0110\u1ed9i m\u1ed9t c\u00f3 35 ng\u01b0\u1eddi, n\u1ebfu m\u1ed7i ng\u01b0\u1eddi l\u00e0m trong 16 ng\u00e0y th\u00ec \u0111\u00e0o \u0111\u01b0\u1ee3c 864 $m^{3}$ \u0111\u1ea5t. H\u1ecfi 20 ng\u01b0\u1eddi c\u1ee7a \u0111\u1ed9i hai, m\u1ed7i ng\u01b0\u1eddi l\u00e0m trong 14 ng\u00e0y s\u1ebd \u0111\u00e0o \u0111\u01b0\u1ee3c bao nhi\u00eau $m^{3}$ \u0111\u1ea5t ? (Gi\u1ea3 thi\u1ebft n\u0103ng su\u1ea5t lao \u0111\u1ed9ng c\u1ee7a m\u1ed7i ng\u01b0\u1eddi l\u00e0 nh\u01b0 nhau). <br\/> \u0110\u00e1p s\u1ed1: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} ( m^{3})$ <\/span> ","hint":"L\u1ea5y t\u1ec9 l\u1ec7 v\u1ec1 S\u1ed1 \u0111\u1ea5t \u0111\u00e0o \u0111\u01b0\u1ee3c v\u00e0 S\u1ed1 c\u00f4ng lao \u0111\u1ed9ng. <br\/> Bi\u1ebft s\u1ed1 c\u00f4ng lao \u0111\u1ed9ng = s\u1ed1 ng\u01b0\u1eddi . s\u1ed1 ng\u00e0y l\u00e0m vi\u1ec7c","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1: X\u00e1c \u0111\u1ecbnh quan h\u1ec7 t\u1ec9 l\u1ec7 thu\u1eadn gi\u1eefa hai \u0111\u1ea1i l\u01b0\u1ee3ng $y$ v\u00e0 $x$. <br\/>B\u01b0\u1edbc 2: \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t t\u1ec9 s\u1ed1 hai gi\u00e1 tr\u1ecb b\u1ea5t k\u00ec c\u1ee7a \u0111\u1ea1i l\u01b0\u1ee3ng n\u00e0y b\u1eb1ng t\u1ec9 s\u1ed1 hai gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a \u0111\u1ea1i l\u01b0\u1ee3ng kia. <br\/><br\/>T\u00f3m t\u1eaft \u0111\u1ec1 b\u00e0i: <br\/> $\\hspace{2cm} $ S\u1ed1 \u0111\u1ea5t \u0111\u00e0o \u0111\u01b0\u1ee3c ($m^{3}$) $ \\qquad$ S\u1ed1 c\u00f4ng lao \u0111\u1ed9ng <br\/> \u0110\u1ed9i m\u1ed9t $ \\qquad$ 864 $\\hspace{3,5cm}$ 560 (= 35.16) <br\/> \u0110\u1ed9i hai $ \\qquad$ $x$ $\\hspace{4,5cm}$ 280 (=20.14) <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <span class='basic_left'> M\u1ed9t ng\u01b0\u1eddi \u0111\u00e0o \u0111\u1ea5t trong 1 ng\u00e0y \u0111\u01b0\u1ee3c t\u00ednh l\u00e0 m\u1ed9t c\u00f4ng lao \u0111\u1ed9ng. <br\/> V\u00ec (S\u1ed1 \u0111\u1ea5t \u0111\u00e0o \u0111\u01b0\u1ee3c) : (S\u1ed1 c\u00f4ng) = N\u0103ng su\u00e2t lao \u0111\u1ed9ng = \u0111\u1ea1i l\u01b0\u1ee3ng kh\u00f4ng \u0111\u1ed5i, <br\/> n\u00ean s\u1ed1 \u0111\u1ea5t \u0111\u00e0o \u0111\u01b0\u1ee3c v\u00e0 s\u1ed1 c\u00f4ng nh\u00e2n l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn. <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn, ta c\u00f3: $ \\dfrac{864}{x} = \\dfrac{560}{280} $ <br\/> Suy ra: $ x = \\dfrac{864.280}{560} = 432 $ <br\/> V\u1eady 20 ng\u01b0\u1eddi c\u1ee7a \u0111\u1ed9i hai m\u1ed7i ng\u01b0\u1eddi l\u00e0m trong 14 ng\u00e0y s\u1ebd \u0111\u00e0o \u0111\u01b0\u1ee3c 432 $m^{3}$ \u0111\u1ea5t. <br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 432. <\/span><\/span> "}]}],"id_ques":608},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":10,"ques":" <span class='basic_left'> Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn. Khi c\u00e1c gi\u00e1 tr\u1ecb $x_{1}, x_{2}$ c\u1ee7a $x$ c\u00f3 t\u1ed5ng b\u1eb1ng 2 th\u00ec hai gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng $y_{1}, y_{2}$ c\u00f3 t\u1ed5ng b\u1eb1ng 8. T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a $y$ khi $x = -1 $<\/span>","select":["A. $ y = -1 $ ","B. $ y = -5 $ ","C. $ y = -2 $ ","D. $ y = -4 $"],"explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1: Bi\u1ec3u di\u1ec5n $y$ theo $x$. <br\/>B\u01b0\u1edbc 2: Thay $x = -1 $ v\u00e0o t\u00ecm $y$. <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> V\u00ec $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn, n\u00ean: <br\/> $ y = ax$ (a l\u00e0 h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7, a kh\u00e1c 0) <br\/> Khi \u0111\u00f3 : $ \\begin{cases} y_{1} = a .x_{1} \\\\ y_{2} = a.x_{2} \\end{cases} $ <br\/> Suy ra $ y_{1} + y_{2} = a ( x_{1} + x_{2}) \\\\ \\Rightarrow 8 = a.2 \\Rightarrow a = 4 $ <br\/> V\u1eady $ y = 4x$ <br\/> Khi $x = -1$ th\u00ec $ y = 4.(-1) = -4 $<br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span><\/span> ","column":2}]}],"id_ques":609},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":10,"ques":"<span class='basic_left'> Cho bi\u1ebft $y_{1}$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $x_{1}$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 a (a $ \\neq$ 0) v\u00e0 $y_{2}$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $x_{2}$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 a. $y_{1} + y_{2}$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $x_{1} + x_{2}$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0: <\/span>","select":["A. $a$ ","B. $2a$ ","C. $\\dfrac{1}{a} $ ","D. $\\dfrac{a}{2} $ "],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $y$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$ suy ra x = ky. <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> $y_{1}$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $x_{1}$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 a n\u00ean $ y_{1} = a x_{1}$ <br\/> $y_{2}$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $x_{2}$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 a n\u00ean $ y_{2} = a x_{2}$ <br\/> Ta c\u00f3: $ y_{1} + y_{2} = ax_{1} + ax_{2} = a(x_{1} + x_{2}) $ <br\/> Do \u0111\u00f3 $y_{1} + y_{2}$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $x_{1} + x_{2}$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0: a. <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":2}]}],"id_ques":610}],"lesson":{"save":0,"level":3}}