{"segment":[{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" C\u00e1c m\u00e1y c\u00e0y c\u00f3 c\u00f9ng n\u0103ng su\u1ea5t c\u00e0y tr\u00ean c\u00e1c c\u00e1nh \u0111\u1ed3ng c\u00f3 c\u00f9ng di\u1ec7n t\u00edch th\u00ec: ","select":["A. S\u1ed1 m\u00e1y t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi s\u1ed1 ng\u00e0y ho\u00e0n th\u00e0nh c\u00f4ng vi\u1ec7c. ","B. S\u1ed1 m\u00e1y t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi s\u1ed1 ng\u00e0y ho\u00e0n th\u00e0nh c\u00f4ng vi\u1ec7c.","C. S\u1ed1 m\u00e1y kh\u00f4ng t\u1ec9 l\u1ec7 v\u1edbi s\u1ed1 ng\u00e0y ho\u00e0n th\u00e0nh c\u00f4ng vi\u1ec7c. "],"explain":" V\u1edbi c\u00f9ng n\u0103ng su\u1ea5t v\u00e0 di\u1ec7n t\u00edch l\u00e0m vi\u1ec7c th\u00ec s\u1ed1 m\u00e1y c\u00e0y t\u0103ng l\u00ean th\u00ec s\u1ed1 ng\u00e0y ho\u00e0n th\u00e0nh c\u00f4ng vi\u1ec7c s\u1ebd gi\u1ea3m xu\u1ed1ng. <br\/> V\u1eady s\u1ed1 m\u00e1y v\u00e0 s\u1ed1 ng\u00e0y ho\u00e0n th\u00e0nh c\u00f4ng vi\u1ec7c l\u00e0 quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":1}]}],"id_ques":611},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"B\u1ea3ng n\u00e0o d\u01b0\u1edbi \u0111\u00e2y cho ta quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch? <br\/> B\u1ea3ng 1. <table> <tr> <td> $x$<\/td> <td> 1 <\/td> <td> 2 <\/td> <td> 3<\/td> <td> 4 <\/td><\/tr> <tr> <td> $y$<\/td> <td> 1 <\/td> <td> 4<\/td> <td> 9<\/td> <td> 16 <\/td><\/tr> <\/table> B\u1ea3ng 2 . <table> <tr> <td> $x$<\/td> <td> 1 <\/td> <td> 2 <\/td> <td> 3<\/td> <td> 4 <\/td><\/tr> <tr> <td> $y$<\/td> <td> -6 <\/td> <td> -3<\/td> <td> -2<\/td> <td> $-1\\frac{1}{2}$ <\/td><\/tr> <\/table> ","select":["B\u1ea3ng 1","B\u1ea3ng 2"],"hint":"Xem \u0111\u1ecbnh ngh\u0129a t\u1ec9 l\u1ec7 ngh\u1ecbch. ","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> * N\u1ebfu \u0111\u1ea1i l\u01b0\u1ee3ng $y$ li\u00ean h\u1ec7 v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $x$ theo c\u00f4ng th\u1ee9c $y = \\dfrac{a}{x} $ hay $xy = a$ (a l\u00e0 m\u1ed9t h\u1eb1ng s\u1ed1 kh\u00e1c 0) th\u00ec ta n\u00f3i $y$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $x$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 a. <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> T\u1eeb b\u1ea3ng 1 ta th\u1ea5y $xy = 1.1 \\neq 2.4 \\neq $$ 3.9 \\neq 4.16 $ <br\/> Suy ra $x$ v\u00e0 $y$ kh\u00f4ng l\u00e0 quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/> T\u1eeb b\u1ea3ng 2 ta th\u1ea5y $xy = 1.(-6) = 2.(-3) = $$ 3.(-2) = 4.\\left( -1\\dfrac{1}{2} \\right) = -6$ <br\/> Suy ra $x$ v\u00e0 $y$ l\u00e0 quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B\u1ea3ng 2. <\/span><\/span> ","column":2}]}],"id_ques":612},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":" <span class='basic_left'> M\u1ed9t \u00f4 t\u00f4 ch\u1ea1y t\u1eeb A \u0111\u1ebfn B v\u1edbi v\u1eadn t\u1ed1c 60 km\/h th\u00ec h\u1ebft 2,5 gi\u1edd. L\u00fac t\u1eeb B v\u1ec1 A, xe ch\u1ea1y v\u1edbi v\u1eadn t\u1ed1c 50 km\/h th\u00ec m\u1ea5t bao l\u00e2u? <\/span>","select":["A. 2 gi\u1edd ","B. 2 gi\u1edd 15 ph\u00fat ","C. 2 gi\u1edd 30 ph\u00fat ","D. 3 gi\u1edd "],"hint":"V\u1eadn t\u1ed1c v\u00e0 th\u1eddi gian l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch","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 ( $\\dfrac{x_{1}}{x_{2}} = \\dfrac{y_{2}}{y_{1}} $) <br\/><br\/>T\u00f3m t\u1eaft \u0111\u1ec1 b\u00e0i: <br\/> V\u1eadn t\u1ed1c $ \\hspace{1cm} $ Th\u1eddi gian <br\/> 60 km\/h $ \\hspace{1cm} $ 2,5 gi\u1edd <br\/> 50 km\/h $ \\hspace{1cm} $ $x$ gi\u1edd? <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> Tr\u00ean c\u00f9ng m\u1ed9t qu\u00e3ng \u0111\u01b0\u1eddng, v\u1eadn t\u1ed1c v\u00e0 th\u1eddi gian l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch, ta c\u00f3: <br\/> $\\dfrac{60}{50} = \\dfrac{x}{2,5} \\Rightarrow x = \\dfrac{60.2,5}{50} = 3 $ <br\/> V\u1eady th\u1eddi gian xe ch\u1ea1y t\u1eeb B v\u1ec1 A l\u00e0 3 gi\u1edd. <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span><\/span> ","column":2}]}],"id_ques":613},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" <span class='basic_left'> M\u1ed9t \u00f4 t\u00f4 ch\u1ea1y t\u1eeb A \u0111\u1ebfn B v\u1edbi v\u1eadn t\u1ed1c 50km\/h th\u00ec h\u1ebft 2 gi\u1edd 15 ph\u00fat. H\u1ecfi chi\u1ebfc \u00f4 t\u00f4 \u0111\u00f3 ch\u1ea1y t\u1eeb A \u0111\u1ebfn B v\u1edbi v\u1eadn t\u1ed1c 45km\/h th\u00ec h\u1ebft bao nhi\u00eau th\u1eddi gian? <\/span>","select":["A. 2 gi\u1edd ","B. 2 gi\u1edd 15 ph\u00fat ","C. 2 gi\u1edd 30 ph\u00fat ","D. 3 gi\u1edd "],"hint":"Th\u1eddi gian v\u00e0 v\u1eadn t\u1ed1c l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch","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\/> T\u00f3m t\u1eaft \u0111\u1ec1 b\u00e0i: <br\/> V\u1eadn t\u1ed1c $ \\hspace{1cm} $ Th\u1eddi gian <br\/> 50 km\/h $ \\hspace{1cm} $ 2,25 gi\u1edd <br\/> 45 km\/h $ \\hspace{1cm} $ $x$ gi\u1edd? <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <span class='basic_left'> \u0110\u1ed5i 2 gi\u1edd 15 ph\u00fat = 2,25 gi\u1edd <br\/> Tr\u00ean c\u00f9ng m\u1ed9t qu\u00e3ng \u0111\u01b0\u1eddng, v\u1eadn t\u1ed1c v\u00e0 th\u1eddi gian l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch, ta c\u00f3: <br\/> $\\dfrac{50}{45} = \\dfrac{x}{2,25} \\Rightarrow x = \\dfrac{2,25.50}{45} = 2,5 $ <br\/>V\u1eady chi\u1ebfc \u00f4 t\u00f4 \u0111\u00f3 ch\u1ea1y t\u1eeb A \u0111\u1ebfn B v\u1edbi v\u1eadn t\u1ed1c 45km\/h h\u1ebft 2,5 gi\u1edd = 2 gi\u1edd 30 ph\u00fat <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":614},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" <span class='basic_left'> Cho bi\u1ebft 36 x\u00e3 vi\u00ean c\u1ee7a m\u1ed9t h\u1ee3p t\u00e1c x\u00e3 n\u00f4ng nghi\u1ec7p \u0111\u00e0o m\u1ed9t \u0111o\u1ea1n m\u01b0\u01a1ng d\u1eabn n\u01b0\u1edbc trong 12 ng\u00e0y. H\u1ecfi c\u1ea7n bao nhi\u00eau x\u00e3 vi\u00ean \u0111\u1ec3 c\u00f3 th\u1ec3 \u0111\u00e0o xong \u0111o\u1ea1n m\u01b0\u01a1ng \u0111\u00f3 trong 8 ng\u00e0y? <\/span>","select":["A. 54 ng\u01b0\u1eddi ","B. 34 ng\u01b0\u1eddi ","C. 20 ng\u01b0\u1eddi ","D. 18 ng\u01b0\u1eddi "],"hint":" S\u1ed1 x\u00e3 vi\u00ean l\u00e0m vi\u1ec7c v\u00e0 th\u1eddi gian ho\u00e0n th\u00e0nh l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch","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 ( $\\dfrac{x_{1}}{x_{2}} = \\dfrac{y_{2}}{y_{1}} $) <br\/><br\/> T\u00f3m t\u1eaft \u0111\u1ec1 b\u00e0i: <br\/> S\u1ed1 c\u00f4ng nh\u00e2n $ \\hspace{1cm} $ Th\u1eddi gian <br\/> 36 ng\u01b0\u1eddi $ \\hspace{2cm} $ 12 ng\u00e0y <br\/> $x$ ng\u01b0\u1eddi? $ \\hspace{2cm}$ 8 ng\u00e0y <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> V\u1edbi c\u00f9ng n\u0103ng su\u1ea5t th\u00ec s\u1ed1 c\u00f4ng nh\u00e2n v\u00e0 th\u1eddi gian l\u00e0m vi\u1ec7c l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch, ta c\u00f3: <br\/> $\\dfrac{36}{x} = \\dfrac{8}{12} \\Rightarrow x = \\dfrac{36.12}{8} = 54 $ <br\/> V\u1eady c\u1ea7n 54 ng\u01b0\u1eddi \u0111\u1ec3 \u0111\u00e0o \u0111o\u1ea1n m\u01b0\u01a1ng trong 8 ng\u00e0y. <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":2}]}],"id_ques":615},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":" <span class='basic_left'>Cho bi\u1ebft 3 ng\u01b0\u1eddi l\u00e0m c\u1ecf m\u1ed9t c\u00e1nh \u0111\u1ed3ng h\u1ebft 6 gi\u1edd. H\u1ecfi 12 ng\u01b0\u1eddi (v\u1edbi c\u00f9ng n\u0103ng su\u1ea5t nh\u01b0 th\u1ebf) l\u00e0m c\u1ecf c\u00e1nh \u0111\u1ed3ng \u0111\u00f3 h\u1ebft bao nhi\u00eau th\u1eddi gian? <\/span>","select":["A. 3 gi\u1edd ","B. 2 gi\u1edd ","C. 1 gi\u1edd ","D. 1,5 gi\u1edd "],"hint":"S\u1ed1 ng\u01b0\u1eddi l\u00e0m c\u1ecf v\u00e0 th\u1eddi gian l\u00e0m vi\u1ec7c l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch.","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\/>T\u00f3m t\u1eaft \u0111\u1ec1 b\u00e0i: <br\/> S\u1ed1 c\u00f4ng nh\u00e2n $ \\hspace{1cm} $ Th\u1eddi gian <br\/> 3 ng\u01b0\u1eddi $ \\hspace{2cm} $ 6 gi\u1edd <br\/> 12 ng\u01b0\u1eddi $ \\hspace{2cm}$ $x$ gi\u1edd? <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> Tr\u00ean c\u00f9ng m\u1ed9t c\u00e1nh \u0111\u1ed3ng v\u1edbi n\u0103ng su\u1ea5t nh\u01b0 nhau th\u00ec s\u1ed1 ng\u01b0\u1eddi l\u00e0m c\u1ecf v\u00e0 s\u1ed1 gi\u1edd l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch, ta c\u00f3: <br\/> $ \\dfrac{3}{12} = \\dfrac{x}{6} \\Rightarrow x = \\dfrac{3.6}{12} = 1,5 $ <br\/> V\u1eady 12 ng\u01b0\u1eddi l\u00e0m c\u1ecf c\u00e1nh \u0111\u1ed3ng h\u1ebft 1,5 gi\u1edd. <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span><\/span> ","column":2}]}],"id_ques":616},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" <span class='basic_left'>M\u1ed9t \u0111o\u00e0n t\u00e0u chuy\u1ec3n \u0111\u1ed9ng v\u1edbi v\u1eadn t\u1ed1c 20 m\u00e9t\/gi\u00e2y th\u00ec c\u1ea7n 10 gi\u1edd \u0111\u1ec3 \u0111i t\u1eeb A \u0111\u1ebfn B. N\u1ebfu \u0111o\u00e0n t\u00e0u \u0111\u00f3 ch\u1ec9 chuy\u1ec3n \u0111\u1ed9ng v\u1edbi v\u1eadn t\u1ed1c 12,5 m\u00e9t\/gi\u00e2y th\u00ec \u0111\u1ec3 \u0111i h\u1ebft qu\u00e3ng \u0111\u01b0\u1eddng AB \u0111o\u00e0n t\u00e0u c\u1ea7n kho\u1ea3ng th\u1eddi gian n\u00e0o d\u01b0\u1edbi \u0111\u00e2y? <\/span>","select":["A. 8 gi\u1edd ","B. 7,5 gi\u1edd ","C. 16 gi\u1edd ","D. 13 gi\u1edd "],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1. \u0110\u1eb7t \u1ea9n cho kh\u1ea3ng th\u1eddi gian \u0111o\u00e0n t\u00e0u chuy\u1ec3n \u0111\u1ed9ng v\u1edbi v\u1eadn t\u1ed1c 12,5 m\u00e9t\/gi\u00e2y. <br\/> B\u01b0\u1edbc 2. x\u00e1c \u0111\u1ecbnh hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch . <br\/> B\u01b0\u1edbc 3. 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 ( $\\dfrac{x_{1}}{x_{2}} = \\dfrac{y_{2}}{y_{1}} $)<br\/> B\u01b0\u1edbc 4. Bi\u1ebfn \u0111\u1ed5i, \u00e1p d\u1ee5ng t\u00ednh ch\u1ea5t c\u1ee7a d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau \u0111\u1ec3 t\u00ecm ra \u0111\u1ea1i l\u01b0\u1ee3ng c\u1ea7n t\u00ecm. <br\/><br\/> T\u00f3m t\u1eaft \u0111\u1ec1 b\u00e0i: <br\/> V\u1eadn t\u1ed1c $ \\hspace{1cm} $ Th\u1eddi gian <br\/> 20 m\u00e9t\/gi\u00e2y $ \\hspace{1cm} $ 10 gi\u1edd <br\/> 12,5 m\u00e9t\/gi\u00e2y $ \\hspace{1cm} $ $x$ gi\u1edd? <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> Tr\u00ean c\u00f9ng qu\u00e3ng \u0111\u01b0\u1eddng AB th\u00ec th\u1eddi gian v\u00e0 v\u1eadn t\u1ed1c l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/> Theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch, ta c\u00f3: <br\/> $ \\dfrac{20}{12,5} = \\dfrac{x}{10} \\Rightarrow x = \\dfrac{10.20}{12,5} = 16 $ <br\/> V\u1eady th\u1eddi gian \u0111\u1ec3 \u0111o\u00e0n t\u00e0u \u0111i h\u1ebft qu\u00e3ng \u0111\u01b0\u1eddng AB v\u1edbi v\u1eadn t\u1ed1c 12,5 m\u00e9t\/gi\u00e2y l\u00e0 16 (gi\u1edd). <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":617},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" C\u00e1c gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng $y$ v\u00e0 $x$ \u0111\u01b0\u1ee3c cho trong b\u1ea3ng sau: <table> <tr> <td> $x$<\/td> <td> 1 <\/td> <td> 2 <\/td> <td> 4 <\/td> <td> 5 <\/td> <td> 8 <\/td> <\/tr> <tr> <td> $y$<\/td> <td> 120 <\/td> <td> 60 <\/td> <td> 30 <\/td> <td> 24 <\/td> <td> 15 <\/td> <\/tr> <\/table>","select":["A. $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $y$ v\u1edbi h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 $\\dfrac{1}{120} $ ","B. $x$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $y$ v\u1edbi h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 $\\dfrac{1}{120} $ ","C. $x$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $y$ v\u1edbi h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 $120$ ","D. $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $y$ v\u1edbi h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 $120$ "],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e1c \u0111\u1ecbnh $x$ v\u00e0 $y$ li\u00ean h\u1ec7 v\u1edbi nhau theo c\u00f4ng th\u1ee9c n\u00e0o? <br\/> T\u1ec9 l\u1ec7 thu\u1eadn n\u1ebfu $x$ v\u00e0 $y$ li\u00ean theo c\u00f4ng th\u1ee9c $ \\dfrac{y}{x} = k $ ( v\u1edbi k l\u00e0 h\u1eb1ng s\u1ed1 kh\u00e1c 0 ) <br\/> T\u1ec9 l\u1ec7 ngh\u1ecbch n\u1ebfu $x$ v\u00e0 $y$ li\u00ean h\u1ec7 theo c\u00f4ng th\u1ee9c $xy=a$ ( a l\u00e0 m\u1ed9t h\u1eb1ng s\u1ed1 kh\u00e1c 0) <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> Ta c\u00f3 t\u00edch $xy$ \u1edf t\u1ea5t c\u1ea3 c\u00e1c c\u1ed9t \u0111\u1ec1u b\u1eb1ng 120. <br\/> N\u00ean $x$ v\u00e0 $y$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi nhau theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 120. <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":618},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" C\u00e1c gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng $y$ v\u00e0 $x$ \u0111\u01b0\u1ee3c cho trong b\u1ea3ng sau: <table> <tr> <td> $x$<\/td> <td> 2 <\/td> <td> 3 <\/td> <td> 4 <\/td> <td> 5 <\/td><\/tr> <tr> <td> $y$<\/td> <td> 12 <\/td> <td> 8 <\/td> <td> 6 <\/td> <td> 4,8 <\/td><\/tr> <\/table> H\u1ecfi hai \u0111\u1ea1i l\u01b0\u1ee3ng $y$ v\u00e0 $x$ c\u00f3 t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi nhau hay kh\u00f4ng? ","select":["C\u00f3 ","Kh\u00f4ng "],"hint":"T\u00ednh t\u00edch $xy$ c\u1ee7a m\u1ed7i c\u1ed9t r\u1ed3i so s\u00e1nh.","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e9t t\u00edch c\u00e1c gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng, n\u1ebfu c\u00e1c t\u00edch n\u00e0y b\u1eb1ng nhau th\u00ec hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> Ta c\u00f3: 2.12 = 3.8 = 4.6 = 5.4,8 ( = 24) <br\/> V\u1eady hai \u0111\u1ea1i l\u01b0\u1ee3ng $y$ v\u00e0 $x$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi nhau theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 a = 24. <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n l\u00e0 C\u00f3. <\/span><\/span> ","column":2}]}],"id_ques":619},{"time":9,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["4"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"Cho bi\u1ebft $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/> \u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng. <table> <tr> <td> $x$ <\/td> <td> 3 <\/td> <td> 2 <\/td> <\/tr> <tr> <td> $y$ <\/td> <td> _input_ <\/td> <td> 6 <\/td> <\/tr> <\/table>","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e1c \u0111\u1ecbnh h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 a, v\u1edbi $a = xy$ <br\/> T\u00ecm $y$ theo c\u00f4ng th\u1ee9c: $ y = \\dfrac{a}{x}$ <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> V\u00ec $y$ v\u00e0 $x$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch n\u00ean $a = xy = 2.6 = 12$ <br\/> V\u1edbi $x = 3$ th\u00ec $ y = \\dfrac{12}{3} = 4 $ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n c\u1ea7n \u0111i\u1ec1n l\u00e0 4. <\/span><\/span> "}]}],"id_ques":620},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" C\u00f4ng th\u1ee9c n\u00e0o sau \u0111\u00e2y cho ta quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch gi\u1eefa $x$ v\u00e0 $y$. ","select":["A. $5y = -2x $","B. $y = -x $ ","C. $5xy = 1 $ ","D. $ \\dfrac{1}{x+y} = 2017 $ "],"hint":"Xem \u0111\u1ecbnh ngh\u0129a quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch.","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> N\u1ebfu \u0111\u1ea1i l\u01b0\u1ee3ng $y$ li\u00ean h\u1ec7 v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $x$ theo c\u00f4ng th\u1ee9c $y = \\dfrac{a}{x} $ hay $xy = a$ (a l\u00e0 m\u1ed9t h\u1eb1ng s\u1ed1 kh\u00e1c 0) th\u00ec ta n\u00f3i $y$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $x$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 a. <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> Ta c\u00f3: $ 5xy = 1 $ <br\/> $ \\Leftrightarrow y = \\dfrac{\\dfrac{1}{5}}{x} $ hay $ xy = \\dfrac{1}{5} $ <br\/> V\u1eady c\u00f4ng th\u1ee9c cho ta quan h\u1ec7 t\u1ec9 l\u1ec7 ngh\u1ecbch gi\u1eefa $x$ v\u00e0 $y$ l\u00e0: $5xy = 1 $ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":621},{"time":9,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["-3"],["1"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"Cho bi\u1ebft $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/> \u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng.<table> <tr><td> $x$ <\/td> <td> 4 <\/td> <td> _input_ <\/td> <td> 6 <\/td> <\/tr> <tr><td> $y$ <\/td> <td> 1,5 <\/td> <td> -2 <\/td> <td> _input_ <\/td> <\/tr><\/table>","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e1c \u0111\u1ecbnh h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 a, v\u1edbi $a = xy$ <br\/> T\u00ecm $y$ theo c\u00f4ng th\u1ee9c: $ y = \\dfrac{a}{x}$ <br\/> T\u00ecm $x$ theo c\u00f4ng th\u1ee9c $x = \\dfrac{a}{y} $<\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> V\u00ec $y$ v\u00e0 $x$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch n\u00ean $a = xy = 4.1,5 = 6$ <br\/> V\u1edbi $y = -2$ th\u00ec $ x = \\dfrac{6}{-2} = -3 $ <br\/> V\u1edbi $x = 6$ th\u00ec $ y = \\dfrac{6}{6} = 1 $<br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n c\u1ea7n \u0111i\u1ec1n l\u00e0 -3; 1. <\/span><\/span> "}]}],"id_ques":622},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"N\u1ebfu $y = \\dfrac{1}{x} $ th\u00ec kh\u1eb3ng \u0111\u1ecbnh n\u00e0o d\u01b0\u1edbi \u0111\u00e2y kh\u00f4ng \u0111\u00fang? ","select":["A. $y = \\dfrac{1}{x} \\Leftrightarrow x = \\dfrac{1}{y} $","B. C\u1ea3 $x$ l\u1eabn $y$ \u0111\u1ec1u kh\u00f4ng b\u1eb1ng 0.","C. Khi $x$ t\u0103ng g\u1ea5p \u0111\u00f4i th\u00ec $y$ ch\u1ec9 c\u00f2n m\u1ed9t n\u1eeda. ","D. $x$ v\u00e0 $y$ \u0111\u1ec1u t\u0103ng."],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> N\u1ebfu \u0111\u1ea1i l\u01b0\u1ee3ng $y$ li\u00ean h\u1ec7 v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $x$ theo c\u00f4ng th\u1ee9c $y = \\dfrac{a}{x} $ hay $xy = a$ (a l\u00e0 m\u1ed9t h\u1eb1ng s\u1ed1 kh\u00e1c 0) th\u00ec ta n\u00f3i $y$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $x$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 a. <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> Ta c\u00f3 $x$ v\u00e0 $y$ li\u00ean h\u1ec7 v\u1edbi nhau b\u1edfi c\u00f4ng th\u1ee9c $y = \\dfrac{1}{x} $ <br\/> Suy ra $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch. <br\/> Kh\u1eb3ng \u0111\u1ecbnh kh\u00f4ng \u0111\u00fang l\u00e0 $x$ v\u00e0 $y$ \u0111\u1ec1u t\u0103ng. <br\/><br\/><span class='basic_pink'> Ch\u1ecdn \u0111\u00e1p \u00e1n D. <\/span><\/span> ","column":2}]}],"id_ques":623},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":" Cho $y$ v\u00e0 $x$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch, bi\u1ebft r\u1eb1ng khi $x = -4$ th\u00ec $y = -8$. <br\/> C\u1ed9t n\u00e0o sau \u0111\u00e2y sai?<\/span> <table><tr><th>C\u1ed9t<\/th><th>1<\/th><th>2<\/th><th>3<\/th><th>4<\/th><\/tr><tr><td>$x$<\/td><td>-8<\/td><td>-2<\/td><td>2<\/td><td>8<\/td><\/tr><tr><td>$y$<\/td><td>-4<\/td><td>-16<\/td><td>16<\/td><td>6<\/td><\/tr><\/table>","select":["A. C\u1ed9t 1","B. C\u1ed9t 2 ","C. C\u1ed9t 3 ","D. C\u1ed9t 4 "],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e1c \u0111\u1ecbnh h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 a, v\u1edbi $a = xy$ <br\/> T\u00ecm $y$ theo c\u00f4ng th\u1ee9c: $ y = \\dfrac{a}{x}. $<\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> V\u00ec $y$ v\u00e0 $x$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch n\u00ean $a = xy = (-4).(-8) = 32 $ <br\/> \u0110\u1ea1i l\u01b0\u1ee3ng $y$ li\u00ean h\u1ec7 v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $x$ b\u1edfi c\u00f4ng th\u1ee9c: $ y = \\dfrac{32}{x}$<br\/> C\u1ed9t 1: Khi $x = -8 $ th\u00ec $ y = \\dfrac{32}{-8} = -4 $ <br\/> C\u1ed9t 2: Khi $x = -2 $ th\u00ec $ y = \\dfrac{32}{-2} = -16 $ <br\/> C\u1ed9t 3: Khi $x = 2 $ th\u00ec $ y = \\dfrac{32}{2} = 16 $ <br\/> C\u1ed9t 4: Khi $x = 8 $ th\u00ec $ y = \\dfrac{32}{8} = 4 \\neq 6 $ <br\/> V\u1eady c\u1ed9t sai l\u00e0 c\u1ed9t 4. <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span><\/span> ","column":4}]}],"id_ques":624},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho bi\u1ebft $y$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $x$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 3. Khi \u0111\u00f3 $x$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $y$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0: <\/span>","select":["A. $\\dfrac{1}{3} $ ","B. 3 ","C. 4 ","D. 1 "],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> Khi $y$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $x$ th\u00ec $x$ c\u0169ng t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $y$ (v\u1edbi c\u00f9ng m\u1ed9t h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7). <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> Ta c\u00f3 $y$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $x$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 3 <br\/> th\u00ec $x$ c\u0169ng t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi $y$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 3. <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":4}]}],"id_ques":625},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi nhau. H\u00e3y ch\u1ecdn c\u00e2u \u0111\u00fang.<\/span>","select":["A. $x = ay$ (a l\u00e0 h\u1eb1ng s\u1ed1, $a \\neq 0$) ","B. $y = ax$ (a l\u00e0 h\u1eb1ng s\u1ed1, $a \\neq 0$) ","C. $y = \\dfrac{a}{x} $ (a l\u00e0 h\u1eb1ng s\u1ed1, $a \\neq 0$) ","D. $y = a + x$ (a l\u00e0 h\u1eb1ng s\u1ed1, $a \\neq 0$) "],"explain":" C\u00f3 $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch n\u00ean \u0111\u1ea1i l\u01b0\u1ee3ng $y$ li\u00ean h\u1ec7 v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $x$ theo c\u00f4ng th\u1ee9c: <br\/> $y = \\dfrac{a}{x} $ (a l\u00e0 h\u1eb1ng s\u1ed1, $a \\neq 0$) <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":626},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch v\u00e0 khi $x$ = -6 th\u00ec $y$ = 8. T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a $x$ khi $y$ b\u1eb1ng 12? <\/span>","select":["A. -4 ","B. 4 ","C. 16 ","D. -16 "],"hint":"- T\u00ecm h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$. <br\/> - Thay v\u00e0o c\u00f4ng th\u1ee9c r\u1ed3i t\u00ecm $y$.","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1: X\u00e1c \u0111\u1ecbnh h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$, v\u1edbi $a = xy$ <br\/> B\u01b0\u1edbc 2: T\u00ecm $x$ theo c\u00f4ng th\u1ee9c: $x = \\dfrac{a}{y}.$ <\/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 ngh\u1ecbch n\u00ean: <br\/> $a = xy = -6.8 = -48 $ <br\/> Do \u0111\u00f3 $y$ v\u00e0 $x$ li\u00ean h\u1ec7 v\u1edbi nhau b\u1edfi c\u00f4ng th\u1ee9c: $ y = \\dfrac{-48}{x}$. <br\/> V\u1eady khi $y = 12$ th\u00ec $ x = \\dfrac{-48}{12} = -4 $ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":4}]}],"id_ques":627},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch v\u00e0 khi $x$ = 8 th\u00ec $y$ = 15. T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a $y$ khi $x$ b\u1eb1ng 6? <\/span>","select":["A. 20 ","B. 0,6","C. $\\dfrac{5}{16} $","D. $\\dfrac{23}{6} $ "],"hint":"- T\u00ecm h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$. <br\/> - Thay v\u00e0o c\u00f4ng th\u1ee9c r\u1ed3i t\u00ecm $y$.","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1: X\u00e1c \u0111\u1ecbnh h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$, v\u1edbi $a = xy$ <br\/> B\u01b0\u1edbc 2: T\u00ecm $y$ theo c\u00f4ng th\u1ee9c: $y = \\dfrac{a}{x}.$ <\/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 ngh\u1ecbch n\u00ean: <br\/> $a = xy = 8.15 = 120 $ <br\/> Do \u0111\u00f3 $y$ v\u00e0 $x$ li\u00ean h\u1ec7 v\u1edbi nhau b\u1edfi c\u00f4ng th\u1ee9c: $ y = \\dfrac{120}{x}$. <br\/> V\u1eady khi $x = 6$ th\u00ec $ y = \\dfrac{120}{6} = 20 $ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":4}]}],"id_ques":628},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch v\u00e0 khi $x$ = 8 th\u00ec $y$ = 5. C\u00f4ng th\u1ee9c li\u00ean h\u1ec7 gi\u1eefa $y$ v\u00e0 $x$ l\u00e0: <\/span>","select":["A. $ y = \\dfrac{5}{8}x$ ","B. $y = \\dfrac{40}{x}$ ","C. $y = 40x$ ","D. $ y = \\dfrac{8}{5} x$ "],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> B\u01b0\u1edbc 1: X\u00e1c \u0111\u1ecbnh h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$, v\u1edbi $a = xy$ <br\/> B\u01b0\u1edbc 2: Bi\u1ec3u di\u1ec5n $y$ theo $x$ b\u1edfi c\u00f4ng th\u1ee9c: $y = \\dfrac{a}{x}.$ <\/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 ngh\u1ecbch n\u00ean: <br\/> $a = xy = 8.5 = 40 $ <br\/> Suy ra $y$ v\u00e0 $x$ li\u00ean h\u1ec7 v\u1edbi nhau b\u1edfi c\u00f4ng th\u1ee9c: $ y = \\dfrac{40}{x}$. <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":4}]}],"id_ques":629},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch v\u00e0 khi $x$ = 8 th\u00ec $y$ = 15. H\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$ c\u1ee7a $y$ \u0111\u1ed1i v\u1edbi $x$ l\u00e0: <\/span>","select":["A. 23 ","B. 120","C. $\\dfrac{15}{8}$ ","D. 7 "],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> X\u00e1c \u0111\u1ecbnh h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a$, v\u1edbi $a = xy$ <\/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 ngh\u1ecbch n\u00ean: <br\/> $a = xy = 8.15 = 120 $ <br\/> V\u1eady h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a = 120$ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":4}]}],"id_ques":630}],"lesson":{"save":0,"level":1}}