{"segment":[{"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":[[["60"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" <span class='basic_left'> Hai b\u00e1nh xe n\u1ed1i v\u1edbi nhau b\u1edfi m\u1ed9t d\u00e2y t\u1eddi. B\u00e1nh xe l\u1edbn c\u00f3 b\u00e1n k\u00ednh 18cm, b\u00e1nh xe nh\u1ecf c\u00f3 b\u00e1n k\u00ednh 12cm. M\u1ed9t ph\u00fat b\u00e1nh xe l\u1edbn quay \u0111\u01b0\u1ee3c 40 v\u00f2ng. H\u1ecfi m\u1ed9t ph\u00fat b\u00e1nh xe nh\u1ecf quay \u0111\u01b0\u1ee3c bao nhi\u00eau v\u00f2ng? <br\/> \u0110\u00e1p s\u1ed1: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}$ (v\u00f2ng) <\/span>","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e1c \u0111\u1ecbnh quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch gi\u1eefa hai \u0111\u1ea1i l\u01b0\u1ee3ng. <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch l\u1eadp c\u00e1c t\u1ec9 s\u1ed1 b\u1eb1ng nhau $\\left(\\dfrac{x_{1}}{x_{2}} = \\dfrac{y_{2}}{y_{1}} \\right)$ <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> Trong c\u00f9ng m\u1ed9t th\u1eddi gian th\u00ec b\u00e1n k\u00ednh b\u00e1nh xe v\u00e0 s\u1ed1 v\u00f2ng quay l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi nhau. <br\/> G\u1ecdi s\u1ed1 v\u00f2ng quay trong m\u1ed9t ph\u00fat c\u1ee7a b\u00e1nh xe nh\u1ecf l\u00e0 $x$. ta c\u00f3: <br\/> $ \\dfrac{18}{12} = \\dfrac{x}{40} \\Rightarrow x = \\dfrac{18.40}{12} = 60 $ <br\/> V\u1eady m\u1ed9t ph\u00fat b\u00e1nh xe nh\u1ecf quay \u0111\u01b0\u1ee3c 60 v\u00f2ng. <br\/><br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 60. <\/span><\/span> "}]}],"id_ques":651},{"time":14,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"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 ngh\u1ecbch. G\u1ecdi $x_{1}, x_{2}$ l\u00e0 c\u00e1c gi\u00e1 tr\u1ecb c\u1ee7a $x$; $y_{1}, y_{2}$ l\u00e0 c\u00e1c gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a $y$. Bi\u1ebft $x_{1} = 3, x_{2} = 2, 2y_{1} + 3y_{2} = -26.$ Vi\u1ebft c\u00f4ng th\u1ee9c li\u00ean h\u1ec7 gi\u1eefa $x$ v\u00e0 $y.$ <\/span>","select":["A. $y = \\dfrac{6}{x} $ ","B. $ y = \\dfrac{12}{x}$","C. $y = \\dfrac{-12}{x} $","D. $ y = \\dfrac{-20}{x} $ "],"hint":"T\u00ecm $y_{1}, y_{2}$ \u0111\u1ec3 t\u00ednh h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7. <br\/> Sau \u0111\u00f3 suy ra c\u00f4ng th\u1ee9c li\u00ean h\u1ec7.","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch n\u00ean $x$ v\u00e0 $y$ li\u00ean h\u1ec7 v\u1edbi nhau b\u1edfi c\u00f4ng th\u1ee9c: $y = \\dfrac{a}{x} $ <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <span class='basic_left'> V\u00ec $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch n\u00ean: $ \\dfrac{x_{1}}{x_{2}} = \\dfrac{y_{2}}{y_{1}} $ <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $x_{1} = 3, x_{2} = 2, 2y_{1} + 3y_{2} = -26$ <br\/> Suy ra: $ \\dfrac{x_{1}}{x_{2}} = \\dfrac{y_{2}}{y_{1}} \\Rightarrow \\dfrac{3}{2} = \\dfrac{y_{2}}{y_{1}} $$\\Rightarrow \\dfrac{y_{1}}{2} = \\dfrac{y_{2}}{3} = \\dfrac{2y_{1}+3y_{2}}{2.2+3.3} = \\dfrac{-26}{13} = -2 $ <br\/> Do \u0111\u00f3: $ y_{1} = 2.(-2) = -4 ; y_{2} = 3.(-2) = -6$ <br\/> H\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a = x_{1}.y_{1} = 3.(-4) = -12 $ <br\/> V\u1eady c\u00f4ng th\u1ee9c li\u00ean h\u1ec7 gi\u1eefa $x$ v\u00e0 $y$ l\u00e0 : $y = \\dfrac{-12}{x} $ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":4}]}],"id_ques":652},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["30"],["28"],["20"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" <span class='basic_left'>Ba \u0111o\u00e0n \u00f4 t\u00f4 v\u1eadn t\u1ea3i h\u00e0ng h\u00f3a \u0111\u1ebfn 3 \u0111\u1ecba \u0111i\u1ec3m c\u00e1ch kho l\u1ea7n l\u01b0\u1ee3t l\u00e0 14km, 15km, 21km. Kh\u1ed1i l\u01b0\u1ee3ng h\u00e0ng h\u00f3a m\u1ed7i \u0111o\u00e0n ph\u1ea3i ch\u1edf t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi kho\u1ea3ng c\u00e1ch c\u1ea7n chuy\u1ec3n. Bi\u1ebft \u0111o\u00e0n th\u1ee9 nh\u1ea5t ph\u1ea3i ch\u1edf nhi\u1ec1u h\u01a1n \u0111o\u00e0n th\u1ee9 ba l\u00e0 10 t\u1ea5n. H\u1ecfi m\u1ed7i \u0111o\u00e0n ch\u1edf bao nhi\u00eau t\u1ea5n h\u00e0ng h\u00f3a? <br\/> \u0110\u00e1p s\u1ed1: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}, \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}, \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (t\u1ea5n)$<\/span>","explain":" G\u1ecdi kh\u1ed1i l\u01b0\u1ee3ng h\u00e0ng h\u00f3a \u0111o\u00e0n th\u1ee9 1, 2, 3 ph\u1ea3i chuy\u1ec3n l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y, z (x, y, z > 0) $ <br\/> th\u00ec $x, y, z$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi 14, 15, 21. <br\/> Theo b\u00e0i c\u00f3: $ x - z = 10$ <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch ta c\u00f3: <br\/> $ \\dfrac{x}{\\dfrac{1}{14}} = \\dfrac{y}{\\dfrac{1}{15}} = \\dfrac{z}{\\dfrac{1}{21}} $ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau: <br\/> $ \\dfrac{x}{\\dfrac{1}{14}} = \\dfrac{y}{\\dfrac{1}{15}} = \\dfrac{z}{\\dfrac{1}{21}} = \\dfrac{x-z}{\\dfrac{1}{14}-\\dfrac{1}{21}} = \\dfrac{10}{\\dfrac{1}{42}} = 420 $ <\/br> Suy ra: $ \\dfrac{x}{\\dfrac{1}{14}} = 420 \\Rightarrow x = 30 \\\\ \\dfrac{y}{\\dfrac{1}{15}} = 420 \\Rightarrow y = 28 \\\\ \\dfrac{z}{\\dfrac{1}{21}} = 420 \\Rightarrow z = 20 $ <br\/> V\u1eady kh\u1ed1i l\u01b0\u1ee3ng h\u00e0ng h\u00f3a c\u1ee7a 3 \u0111o\u00e0n ph\u1ea3i ch\u1edf l\u00e0 30, 28, 20 (t\u1ea5n).<\/span><br\/><br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 30, 28, 20. <\/span><\/span> "}]}],"id_ques":653},{"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":[[["120"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" <span class='basic_left'> M\u1ed9t \u00f4 t\u00f4 d\u1ef1 \u0111\u1ecbnh \u0111i t\u1eeb A \u0111\u1ebfn B trong m\u1ed9t th\u1eddi gian d\u1ef1 \u0111\u1ecbnh v\u1edbi v\u1eadn t\u1ed1c 40 km\/h. Sau khi \u0111i \u0111\u01b0\u1ee3c $ \\dfrac{1}{2} $ qu\u00e3ng \u0111\u01b0\u1eddng AB th\u00ec \u00f4 t\u00f4 t\u0103ng v\u1eadn t\u1ed1c l\u00ean 50 km\/h tr\u00ean qu\u00e3ng \u0111\u01b0\u1eddng c\u00f2n l\u1ea1i. Do \u0111\u00f3 \u00f4 t\u00f4 \u0111\u1ebfn B s\u1edbm h\u01a1n d\u1ef1 \u0111\u1ecbnh l\u00e0 18 ph\u00fat. T\u00ednh \u0111\u1ed9 d\u00e0i qu\u00e3ng \u0111\u01b0\u1eddng AB? <br\/> \u0110\u00e1p s\u1ed1: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (km)$<\/span>","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e1c \u0111\u1ecbnh quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch gi\u1eefa hai \u0111\u1ea1i l\u01b0\u1ee3ng. <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch l\u1eadp c\u00e1c t\u1ec9 s\u1ed1 b\u1eb1ng nhau $\\left(\\dfrac{x_{1}}{x_{2}} = \\dfrac{y_{2}}{y_{1}} \\right)$ <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <span class='basic_left'> \u0110\u1ed5i 18 ph\u00fat = $ \\dfrac{3}{10} $ gi\u1edd <br\/> C\u00f9ng m\u1ed9t qu\u00e3ng \u0111\u01b0\u1eddng n\u00ean v\u1eadn t\u1ed1c v\u00e0 th\u1eddi gian l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. Ta c\u00f3: <table><tr><th><\/th><th>V\u1eadn t\u1ed1c <\/th><th>Th\u1eddi gian <\/th><\/tr><tr><td>L\u00fac tr\u01b0\u1edbc<\/td><td>40 km\/h <\/td><td> $t_{1}$<\/td><\/tr><tr><td>L\u00fac sau<\/td><td>50 km\/h <\/td><td> $t_{2}$<\/td><\/tr><\/table> Theo b\u00e0i ta c\u00f3: $t_{1} - t_{2} = \\dfrac{3}{10} $ <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch ta c\u00f3: <br\/> $\\dfrac{t_{1}}{t_{2}} = \\dfrac{50}{40} = \\dfrac{5}{4} $ <br\/> Hay $ \\dfrac{t_{1}}{5} = \\dfrac{t_{2}}{4} = \\dfrac{t_{1}-t_{2}}{5-4} = \\dfrac{\\dfrac{3}{10}}{1} = \\dfrac{3}{10} \\\\ \\Rightarrow t_{1} = \\dfrac{3}{10}.5 = 1,5 ; t_{2} = \\dfrac{3}{10}.4 = 1,2$ <br\/> Qu\u00e3ng \u0111\u01b0\u1eddng AB b\u1eb1ng: $40.t_{1} + 50.t_{2} = 40.1,5 + 50.1,2 = 120$ (km) <\/span><br\/><br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0m 120. <\/span><\/span> "}]}],"id_ques":654},{"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":[[["9"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" <span class='basic_left'> M\u1ed9t \u0111\u1ed9i c\u00f4ng nh\u00e2n giao th\u00f4ng d\u1ef1 ki\u1ebfn s\u1eeda m\u1ed9t \u0111o\u1ea1n \u0111\u01b0\u1eddng trong m\u1ed9t th\u1eddi gian. Sau khi s\u1eeda \u0111\u01b0\u1ee3c $\\dfrac{1}{2}$ \u0111o\u1ea1n \u0111\u01b0\u1eddng th\u00ec \u0111\u1ed9i \u0111\u00e3 t\u0103ng n\u0103ng su\u1ea5t lao \u0111\u1ed9ng 25% so v\u1edbi tr\u01b0\u1edbc n\u00ean \u0111\u00e3 ho\u00e0n th\u00e0nh c\u00f4ng vi\u1ec7c s\u1edbm h\u01a1n 1 ng\u00e0y. H\u1ecfi \u0111\u1ed9i c\u00f4ng nh\u00e2n \u0111\u00e3 s\u1eeda \u0111o\u1ea1n \u0111\u01b0\u1eddng \u0111\u00f3 trong bao nhi\u00eau l\u00e2u? <br\/> \u0110\u00e1p s\u1ed1: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (ng\u00e0y)$<\/span>","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e1c \u0111\u1ecbnh quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch gi\u1eefa hai \u0111\u1ea1i l\u01b0\u1ee3ng. <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch l\u1eadp c\u00e1c t\u1ec9 s\u1ed1 b\u1eb1ng nhau $\\left(\\dfrac{x_{1}}{x_{2}} = \\dfrac{y_{2}}{y_{1}} \\right)$ <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <span class='basic_left'> C\u00f9ng m\u1ed9t c\u00f4ng vi\u1ec7c th\u00ec th\u1eddi gian ho\u00e0n th\u00e0nh v\u00e0 n\u0103ng su\u1ea5t lao \u0111\u1ed9ng l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. Ta c\u00f3: <table><tr><th><\/th><th>N\u0103ng su\u1ea5t lao \u0111\u1ed9ng<\/th><th>Th\u1eddi gian l\u00e0m vi\u1ec7c<\/th><\/tr><tr><td>L\u00fac tr\u01b0\u1edbc<\/td><td>100%<\/td><td> $t_{1}$<\/td><\/tr><tr><td>L\u00fac sau<\/td><td>125%<\/td><td> $t_{2}$<\/td><\/tr><\/table> Theo b\u00e0i ta c\u00f3: $t_{1} - t_{2} = 1$ <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch ta c\u00f3: <br\/> $\\dfrac{t_{1}}{t_{2}} = \\dfrac{125}{100} = \\dfrac{5}{4} $ <br\/> Hay $ \\dfrac{t_{1}}{5} = \\dfrac{t_{2}}{4} = \\dfrac{t_{1}-t_{2}}{5-4} = \\dfrac{1}{1} = 1 \\\\ \\Rightarrow t_{1} = 5 ; t_{2} = 4$ <br\/> Nh\u01b0 v\u1eady s\u1eeda $\\dfrac{1}{2}$ \u0111o\u1ea1n \u0111\u01b0\u1eddng tr\u01b0\u1edbc trong 5 ng\u00e0y v\u00e0 s\u1eeda $\\dfrac{1}{2}$ \u0111o\u1ea1n \u0111\u01b0\u1eddng sau trong 4 ng\u00e0y. <br\/> Th\u1eddi gian s\u1eeda c\u1ea3 \u0111o\u1ea1n \u0111\u01b0\u1eddng l\u00e0 5 + 4 = 9 (ng\u00e0y) <\/span><br\/><br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 9. <\/span><\/span> "}]}],"id_ques":655},{"time":14,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":10,"ques":" <span class='basic_left'>Ba \u0111o\u00e0n \u00f4 t\u00f4 v\u1eadn t\u1ea3i h\u00e0ng h\u00f3a \u0111\u1ebfn 3 \u0111\u1ecba \u0111i\u1ec3m c\u00e1ch kho l\u1ea7n l\u01b0\u1ee3t l\u00e0 14km, 15km, 21km. Kh\u1ed1i l\u01b0\u1ee3ng h\u00e0ng h\u00f3a m\u1ed7i \u0111o\u00e0n ph\u1ea3i ch\u1edf t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi kho\u1ea3ng c\u00e1ch c\u1ea7n chuy\u1ec3n. Bi\u1ebft \u0111o\u00e0n th\u1ee9 nh\u1ea5t ph\u1ea3i ch\u1edf nhi\u1ec1u h\u01a1n \u0111o\u00e0n th\u1ee9 ba l\u00e0 10 t\u1ea5n. T\u1ed5ng kh\u1ed1i l\u01b0\u1ee3ng h\u00e0ng h\u00f3a ba \u0111o\u00e0n ch\u1edf l\u00e0: <\/span>","select":["A. 58 t\u1ea5n ","B. 48 t\u1ea5n","C. 78 t\u1ea5n","D. 68 t\u1ea5n "],"explain":" G\u1ecdi s\u1ed1 h\u00e0ng h\u00f3a m\u1ed7i \u0111\u1ed9i ph\u1ea3i ch\u1edf l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y, z$ (t\u1ea5n) <br\/> Theo b\u00e0i ta c\u00f3: $x - z = 10$ v\u00e0 $ \\dfrac{x}{\\dfrac{1}{14}} = \\dfrac{y}{\\dfrac{1}{15}} = \\dfrac{z}{\\dfrac{1}{21}}$ <br\/> Theo t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $ \\dfrac{x}{\\dfrac{1}{14}} = \\dfrac{y}{\\dfrac{1}{15}} = \\dfrac{z}{\\dfrac{1}{21}} = \\dfrac{x-z}{\\dfrac{1}{14}-\\dfrac{1}{21}} = \\dfrac{10}{\\dfrac{1}{42}} = 420 $ <br\/> Do \u0111\u00f3: $x = \\dfrac{1}{14} .420 = 30, \\\\ y = \\dfrac{1}{15}.420 = 28; \\\\ z = \\dfrac{1}{21}.420 = 20 $ <br\/> T\u1ed5ng kh\u1ed1i l\u01b0\u1ee3ng h\u00e0ng h\u00f3a ba \u0111o\u00e0n ch\u1edf l\u00e0: 30 + 28 + 20 = 78 (t\u1ea5n) <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":656},{"time":14,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":10,"ques":" <span class='basic_left'>Ba \u0111\u1ed9i th\u1ee3 nh\u1eadn l\u00e0m ba h\u1ee3p \u0111\u1ed3ng nh\u01b0 nhau. \u0110\u1ec3 ho\u00e0n th\u00e0nh h\u1ee3p \u0111\u1ed3ng \u0111\u1ed9i th\u1ee9 nh\u1ea5t m\u1ea5t 3 ng\u00e0y, \u0111\u1ed9i th\u1ee9 hai m\u1ea5t 4 ng\u00e0y. S\u1ed1 ng\u01b0\u1eddi c\u1ee7a \u0111\u1ed9i th\u1ee9 nh\u1ea5t h\u01a1n s\u1ed1 ng\u01b0\u1eddi c\u1ee7a \u0111\u1ed9i th\u1ee9 hai \u0111\u00fang b\u1eb1ng s\u1ed1 ng\u01b0\u1eddi c\u1ee7a \u0111\u1ed9i th\u1ee9 ba. H\u1ecfi \u0111\u1ed9i th\u1ee9 ba ho\u00e0n th\u00e0nh h\u1ee3p \u0111\u1ed3ng trong m\u1ea5y ng\u00e0y? ( n\u0103ng su\u1ea5t l\u00e0m vi\u1ec7c c\u1ee7a c\u00e1c ng\u01b0\u1eddi th\u1ee3 \u0111\u1ec1u nh\u01b0 nhau )<\/span>","select":["A. 7 ng\u00e0y ","B. 10 ng\u00e0y","C. 12 ng\u00e0y","D. 15 ng\u00e0y "],"explain":" <span class='basic_left'> G\u1ecdi s\u1ed1 ng\u01b0\u1eddi c\u1ee7a ba \u0111\u1ed9i l\u1ea7n l\u01b0\u1ee3t l\u00e0 a,b,c ( ng\u01b0\u1eddi) <br\/> Th\u1eddi gian ho\u00e0n th\u00e0nh h\u1ee3p \u0111\u1ed3ng c\u1ee7a \u0111\u1ed9i th\u1ee9 ba l\u00e0 $x$ ( ng\u00e0y). <br\/> H\u1ee3p \u0111\u1ed3ng v\u00e0 n\u0103ng su\u1ea5t l\u00e0m vi\u1ec7c c\u1ee7a c\u00e1c ng\u01b0\u1eddi th\u1ee3 l\u00e0 nh\u01b0 nhau <br\/> Suy ra s\u1ed1 th\u1ee3 c\u1ee7a m\u1ed7i \u0111\u1ed9i v\u00e0 th\u1eddi gian ho\u00e0n th\u00e0nh l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/> Do \u0111\u00f3: $\\dfrac{a}{\\dfrac{1}{3}} = \\dfrac{b}{\\dfrac{1}{4}} = \\dfrac{c}{\\dfrac{1}{x}} = \\dfrac{a-b}{\\dfrac{1}{3}-\\dfrac{1}{4}} = \\dfrac{c}{\\dfrac{1}{12}}$ <br\/> Suy ra: $ \\dfrac{1}{x} = \\dfrac{1}{12} \\Rightarrow x = 12 $ <br\/> V\u1eady th\u1eddi gian ho\u00e0n th\u00e0nh h\u1ee3p \u0111\u1ed3ng c\u1ee7a \u0111\u1ed9i th\u1ee9 ba l\u00e0 12 ng\u00e0y.<br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":657},{"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":[[["90"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" <span class='basic_left'> C\u00f3 ba l\u1edbp 7A, 7B, 7C. \u0110\u1ea7u n\u0103m t\u1ed5ng s\u1ed1 h\u1ecdc sinh hai l\u1edbp 7A, 7B l\u00e0 44 em. N\u1ebfu chuy\u1ec3n 2 em \u1edf l\u1edbp 7A sang l\u1edbp 7C th\u00ec s\u1ed1 h\u1ecdc sinh 3 l\u1edbp 7A, 7B, 7C t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi 8, 6, 3. H\u1ecfi \u0111\u1ea7u n\u0103m t\u1ed5ng 3 l\u1edbp c\u00f3 bao nhi\u00eau h\u1ecdc sinh? <br\/> \u0110\u00e1p s\u1ed1: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}$ (h\u1ecdc sinh)<\/span>","explain":" G\u1ecdi s\u1ed1 h\u1ecdc sinh \u0111\u1ea7u n\u0103m c\u1ee7a ba l\u1edbp 7A, 7B, 7C l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y, z$ ( h\u1ecdc sinh ) <br\/> Theo b\u00e0i ta c\u00f3: $x + y = 44$ v\u00e0 $ \\dfrac{x-2}{\\dfrac{1}{8}} = \\dfrac{y}{\\dfrac{1}{6}} = \\dfrac{z+2}{\\dfrac{1}{3}}$ <br\/> Theo t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $ \\dfrac{x-2}{\\dfrac{1}{8}} = \\dfrac{y}{\\dfrac{1}{6}} = \\dfrac{z+2}{\\dfrac{1}{3}} = \\dfrac{x-2+y}{\\dfrac{1}{8}+\\dfrac{1}{6}} = \\dfrac{44-2}{\\dfrac{7}{24}} = 144 $ <br\/> Do \u0111\u00f3: $ \\dfrac{z+2}{\\dfrac{1}{3}} = 144 \\Rightarrow z = 46$ <br\/> T\u1ed5ng s\u1ed1 h\u1ecdc sinh c\u1ee7a ba l\u1edbp l\u00e0: $ (x + y) + z = 44 + 46 = 90$ (h\u1ecdc sinh) <br\/><br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 90. <\/span><\/span> "}]}],"id_ques":658},{"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":[[["10"],["6"]]],"list":[{"point":10,"width":50,"type_input":"","ques":" <span class='basic_left'> Hai \u00f4 t\u00f4 c\u00f9ng \u0111i t\u1eeb A \u0111\u1ebfn B. Bi\u1ebft v\u1eadn t\u1ed1c xe th\u1ee9 nh\u1ea5t b\u1eb1ng 60% v\u1eadn t\u1ed1c xe th\u1ee9 hai v\u00e0 th\u1eddi gian xe th\u1ee9 nh\u1ea5t \u0111i qu\u00e3ng \u0111\u01b0\u1eddng AB nhi\u1ec1u h\u01a1n xe th\u1ee9 hai \u0111i l\u00e0 4 gi\u1edd. T\u00ednh th\u1eddi gian m\u1ed7i xe \u0111i t\u1eeb A \u0111\u1ebfn B? <br\/> \u0110\u00e1p s\u1ed1: $ t_{1} = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (gi\u1edd) \\\\ t_{2} = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} (gi\u1edd)$<\/span>","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e1c \u0111\u1ecbnh quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch gi\u1eefa hai \u0111\u1ea1i l\u01b0\u1ee3ng. <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch l\u1eadp c\u00e1c t\u1ec9 s\u1ed1 b\u1eb1ng nhau $\\left(\\dfrac{x_{1}}{x_{2}} = \\dfrac{y_{2}}{y_{1}} \\right)$ <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> G\u1ecdi v\u1eadn t\u1ed1c v\u00e0 th\u1eddi gian c\u1ee7a hai xe theo th\u1ee9 t\u1ef1 l\u00e0 $v_{1}, t_{1} $ v\u00e0 $ v_{2}, t_{2}$ <br\/> Theo b\u00e0i ra ta c\u00f3: $ \\dfrac{v_{1}}{v_{2}} = \\dfrac{60}{100} = \\dfrac{3}{5} $ v\u00e0 $ t_{1} - t_{2} = 4$ <br\/> Tr\u00ean c\u00f9ng qu\u00e3ng \u0111\u01b0\u1eddng AB th\u00ec v\u1eadn t\u1ed1c v\u00e0 th\u1eddi gian l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch n\u00ean : <br\/> $ \\dfrac{v_{1}}{v_{2}} = \\dfrac{t_{2}}{t_{1}} \\Rightarrow \\dfrac{t_{2}}{t_{1}} = \\dfrac{3}{5} $ <br\/> N\u00ean $ \\dfrac{t_{1}}{5} = \\dfrac{t_{2}}{3} = \\dfrac{t_{1}-t_{2}}{5-3} = \\dfrac{4}{2} = 2 $ <br\/> Do \u0111\u00f3: $ t_{1} = 2.5 = 10 (gi\u1edd) \\\\ t_{2} = 2.3 = 6 (gi\u1edd)$ <br\/><br\/><span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 10, 6. <\/span><\/span> "}]}],"id_ques":659},{"time":14,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":10,"ques":" Chia s\u1ed1 7567 th\u00e0nh ba ph\u1ea7n t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $\\dfrac{2}{3}; \\dfrac{5}{6}$ v\u00e0 $\\dfrac{3}{8}$. V\u1eady 3 ph\u1ea7n c\u1ea7n t\u00ecm l\u1ea7n l\u01b0\u1ee3t l\u00e0:","select":["A. 2115, 1692, 3760 ","B. 2115, 1690, 3762","C. 2115, 1692, 3770","D. 2110, 1697, 3760 "],"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: $\\dfrac{x}{\\dfrac{1}{a}} = \\dfrac{y}{\\dfrac{1}{b}} = \\dfrac{z}{\\dfrac{1}{c}},$ trong \u0111\u00f3 $x + y + z = M$ <br\/> B\u01b0\u1edbc 2: V\u1eadn d\u1ee5ng t\u00ednh ch\u1ea5t c\u1ee7a d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau \u0111\u1ec3 t\u00ecm $x, y, z.$<\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> G\u1ecdi ba ph\u1ea7n c\u1ea7n t\u00ecm l\u00e0 $x, y, z$ <br\/> V\u00ec $x, y, z$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $\\dfrac{2}{3}; \\dfrac{5}{6}$ v\u00e0 $\\dfrac{3}{8}$ n\u00ean ta c\u00f3: <br\/> $ \\dfrac{x}{\\dfrac{3}{2}} = \\dfrac{y}{\\dfrac{6}{5}} = \\dfrac{z}{\\dfrac{8}{3}} = \\dfrac{x+y+z}{\\dfrac{3}{2}+\\dfrac{6}{5}+\\dfrac{8}{3}} = \\dfrac{7567}{\\dfrac{161}{30}} = 1410 $<br\/> V\u1eady: $ x = \\dfrac{3}{2}.1410 = 2115; \\\\ y = \\dfrac{6}{5}.1410 = 1692; \\\\ z = \\dfrac{8}{3}.1410 = 3760$ <br\/> Ba ph\u1ea7n c\u1ea7n t\u00ecm l\u00e0: 2115, 1692, 3760. <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":2}]}],"id_ques":660}],"lesson":{"save":0,"level":3}}