{"common":{"save":0,"post_id":"952","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"651","post_id":"952","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","options":{"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> "}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:50"},{"id":"652","post_id":"952","mon_id":"0","chapter_id":"0","question":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","options":{"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}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:50"},{"id":"653","post_id":"952","mon_id":"0","chapter_id":"0","question":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","options":{"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> "}]}]},"correct":"","level":"3","hint":"","answer":"","type":"json","extra_type":"","time":"0","user_id":"0","test":"0","date":"2019-09-30 09:22:50"}]}