{"segment":[{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"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 thu\u1eadn. Khi c\u00e1c gi\u00e1 tr\u1ecb $x_{1}, x_{2}$ c\u1ee7a $x$ c\u00f3 t\u1ed5ng b\u1eb1ng $-1$ th\u00ec hai gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng $y_{1}, y_{2}$ c\u00f3 t\u1ed5ng b\u1eb1ng 4. Bi\u1ec3u th\u1ee9c li\u00ean h\u1ec7 c\u1ee7a $y$ theo $x$ l\u00e0: <\/span>","select":["A. $ y = -x $ ","B. $ y = 3x $ ","C. $ y = 4x $ ","D. $ y = -4x $"],"explain":" 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 4 = a.(-1) \\Rightarrow a = -4 $ <br\/> V\u1eady $ y = -4x$ <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span><\/span> ","column":2}]}],"id_ques":581},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" <span class='basic_left'> Ba \u0111\u01a1n v\u1ecb kinh doanh \u0111\u1ea7u t\u01b0 v\u1ed1n t\u01b0\u01a1ng \u1ee9ng theo t\u1ec9 l\u1ec7 3;5;7. Khi chia l\u00e3i, \u0111\u01a1n v\u1ecb th\u1ee9 ba \u0111\u01b0\u1ee3c h\u01a1n \u0111\u01a1n v\u1ecb th\u1ee9 nh\u1ea5t l\u00e0 200 000 \u0111\u1ed3ng. Bi\u1ebft r\u1eb1ng ti\u1ec1n l\u00e3i \u0111\u01b0\u1ee3c chia theo t\u1ec9 l\u1ec7 ti\u1ec1n v\u1ed1n. H\u1ecfi t\u1ed5ng s\u1ed1 ti\u1ec1n l\u00e3i l\u00e0 bao nhi\u00eau?<\/span>","select":["A. 550 000 \u0111 ","B. 650 000 \u0111 ","C. 750 000 \u0111 ","D. 850 000 \u0111 "],"explain":" <span class='basic_left'> G\u1ecdi s\u1ed1 ti\u1ec1n l\u00e3i c\u1ee7a c\u00e1c \u0111\u01a1n v\u1ecb t\u01b0\u01a1ng \u1ee9ng l\u00e0 $x, y, z$ (\u0111\u1ed3ng). <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $z \u2013 x$ = 200000 v\u00e0 $ \\dfrac{x}{3} = \\dfrac{y}{5} = \\dfrac{z}{7} $ <br\/> Theo t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $ \\dfrac{x}{3} = \\dfrac{y}{5} = \\dfrac{z}{7} = \\dfrac{z-x}{7-3} = \\dfrac{200000}{4} = 50000 \\\\ \\Rightarrow x = 3.50000 = 150000 \\\\ y = 5.50000 = 250000 \\\\ z = 7.50000 = 350000 $ <br\/> T\u1ed5ng s\u1ed1 ti\u1ec1n l\u00e3i l\u00e0: $x + y + z = 150000 + 250000 + 350000 = 750000$(\u0111\u1ed3ng) <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":582},{"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":[[["4"],["6"]]],"list":[{"point":5,"width":50,"type_input":"","ques":" <span class='basic_left'> Cho bi\u1ebft $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn, $x_{1}$ v\u00e0 $x_{2}$ l\u00e0 hai gi\u00e1 tr\u1ecb kh\u00e1c nhau c\u1ee7a $x$, $y_{1}$ v\u00e0 $y_{2}$ l\u00e0 hai gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a $y$. T\u00ednh $x_{2}$, $y_{2}$ bi\u1ebft $x_{2} + y_{2} = 10, x_{1} = 2, y_{1} = 3 $ <br\/> \u0110\u00e1p s\u1ed1: $ x_{2} = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}; y_{2} = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} $<\/span>","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\/> <span class='basic_left'> V\u00ec $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn n\u00ean ta c\u00f3: $\\dfrac{y_{1}}{x_{1}} = \\dfrac{y_{2}}{x_{2}} $ <br\/> $ \\Rightarrow \\dfrac{y_{1}}{y_{2}} = \\dfrac{x_{1}}{x_{2}} = \\dfrac{x_{1}+y_{1}}{x_{2}+y_{2}} = \\dfrac{2+3}{10} = \\dfrac{1}{2} $ <br\/> Do \u0111\u00f3: $ x_{2} = x_{1} : \\dfrac{1}{2} = 2 : \\dfrac{1}{2} = 4 \\\\ y_{2} = y_{1} : \\dfrac{1}{2} = 3 : \\dfrac{1}{2} = 6 $ <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 $ x_{2} = 4, y_{2} = 6 $. <\/span><\/span> "}]}],"id_ques":583},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":" Chi\u1ec1u d\u00e0i v\u00e0 chi\u1ec1u r\u1ed9ng c\u1ee7a m\u1ed9t h\u00ecnh ch\u1eef nh\u1eadt t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi 5 v\u00e0 3. Bi\u1ebft chu vi c\u1ee7a h\u00ecnh ch\u1eef nh\u1eadt l\u00e0 144 m. T\u00ednh di\u1ec7n t\u00edch c\u1ee7a h\u00ecnh ch\u1eef nh\u1eadt \u0111\u00f3? ","select":["A. $4860 (m^{2}) $","B. $72 (m^{2})$ ","C. $2754 (m^{2})$ ","D. $1215 (m^{2})$ "],"hint":"Chu vi h\u00ecnh ch\u1eef nh\u1eadt : 2(chi\u1ec1u d\u00e0i + chi\u1ec1u r\u1ed9ng) <br\/> Di\u1ec7n t\u00edch h\u00ecnh ch\u1eef nh\u1eadt: chi\u1ec1u d\u00e0i . chi\u1ec1u r\u1ed9ng","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\/> <span class='basic_left'> G\u1ecdi chi\u1ec1u d\u00e0i v\u00e0 chi\u1ec1u r\u1ed9ng c\u1ee7a h\u00ecnh ch\u1eef nh\u1eadt l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y$ (m). <br\/> Chu vi h\u00ecnh ch\u1eef nh\u1eadt l\u00e0 144 n\u00ean $2(x+y) = 144$ hay $x + y = 72$<br\/> Theo \u0111\u1ec1 b\u00e0i, ta c\u00f3: $\\dfrac{x}{5} = \\dfrac{y}{3} = \\dfrac{x+y}{5+3} = \\dfrac{72}{8} = 9 $ <br\/> Do \u0111\u00f3: $ \\dfrac{x}{5} = 9 \\Rightarrow x = 45 \\\\ \\dfrac{y}{3} = 9 \\Rightarrow y = 27 $ <br\/> V\u1eady chi\u1ec1u d\u00e0i l\u00e0 45 m, chi\u1ec1u r\u1ed9ng l\u00e0 27 m. <br\/> Di\u1ec7n t\u00edch c\u1ee7a h\u00ecnh ch\u1eef nh\u1eadt l\u00e0: chi\u1ec1u d\u00e0i . chi\u1ec1u r\u1ed9ng = 45 . 27 = 1215 ($m^{2}$) <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span><\/span> ","column":2}]}],"id_ques":584},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> M\u1ed9t tr\u01b0\u1eddng ph\u1ed5 th\u00f4ng c\u00f3 3 l\u1edbp 7. T\u1ed5ng s\u1ed1 h\u1ecdc sinh \u1edf hai l\u1edbp 7A v\u00e0 7B l\u00e0 85 h\u1ecdc sinh. N\u1ebfu chuy\u1ec3n 10 h\u1ecdc sinh t\u1eeb l\u1edbp 7A sang l\u1edbp 7C, th\u00ec s\u1ed1 h\u1ecdc sinh 3 l\u1edbp 7A, 7B, 7C t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi 7; 8; 9. S\u1ed1 h\u1ecdc sinh l\u00fac \u0111\u1ea7u c\u1ee7a 3 l\u1edbp 7A, 7B, 7C l\u1ea7n l\u01b0\u1ee3t l\u00e0: <\/span>","select":["A. 45, 45, 30 ","B. 45, 40, 35 ","C. 40, 45, 30 ","D. 35, 50, 40 "],"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\/> <span class='basic_left'> G\u1ecdi s\u1ed1 h\u1ecdc sinh 3 l\u1edbp 7A, 7B, 7C l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y, z$ (h\u1ecdc sinh), $(x, y, z \\in N^{*})$. <br\/> T\u1ed5ng s\u1ed1 h\u1ecdc sinh \u1edf hai l\u1edbp 7A v\u00e0 7B l\u00e0 85 h\u1ecdc sinh n\u00ean $x + y = 85$ <br\/> N\u1ebfu chuy\u1ec3n 10 h\u1ecdc sinh t\u1eeb l\u1edbp 7A sang l\u1edbp 7C th\u00ec l\u1edbp 7A c\u00f2n $x-10$ v\u00e0 l\u1edbp 7C c\u00f3 $z+10$ <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: <br\/> $ \\dfrac{x-10}{7} = \\dfrac{y}{8} = \\dfrac{z+10}{9} = \\dfrac{x+y-10}{7+8} = \\dfrac{85-10}{15} = 5 $ <br\/> Suy ra: $ \\dfrac{x-10}{7} = 5 \\Rightarrow x = 45 \\\\ \\dfrac{y}{8} = 5 \\Rightarrow y = 40 \\\\ \\dfrac{z+10}{9} = 5 \\Rightarrow z = 35 $ <br\/> V\u1eady s\u1ed1 h\u1ecdc sinh 3 l\u1edbp l\u1ea7n l\u01b0\u1ee3t l\u00e0: 45, 40, 35 h\u1ecdc sinh. <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":585},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" <span class='basic_left'> Trong m\u1ed9t gi\u1edd, m\u1ed9t \u0111o\u00e0n t\u00e0u \u0111i \u0111\u01b0\u1ee3c 48 km. C\u0169ng v\u1edbi v\u1eadn t\u1ed1c \u1ea5y, qu\u00e3ng \u0111\u01b0\u1eddng m\u00e0 \u0111o\u00e0n t\u00e0u \u0111i \u0111\u01b0\u1ee3c trong m\u1ed9t ph\u00fat l\u00e0: <\/span>","select":["A. 480 m\u00e9t ","B. 500 m\u00e9t ","C. 800 m\u00e9t ","D. 520 m\u00e9t "],"hint":"L\u1eadp c\u00e1c t\u1ec9 s\u1ed1 t\u01b0\u01a1ng \u1ee9ng c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng. ","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\/> Th\u1eddi gian $ \\qquad$ Qu\u00e3ng \u0111\u01b0\u1eddng <br\/> 60 ph\u00fat $\\hspace{1,5cm}$ 48 km <br\/> 1 ph\u00fat $\\hspace{1,5cm}$ $y$ km ? <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <span class='basic_left'> \u0110\u1ed5i 1 gi\u1edd = 60 ph\u00fat <br\/> Trong c\u00f9ng m\u1ed9t v\u1eadn t\u1ed1c th\u00ec th\u1eddi gian v\u00e0 qu\u00e3ng \u0111\u01b0\u1eddng l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn <br\/> N\u00ean theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn ta c\u00f3: $ \\dfrac{60}{1} = \\dfrac{48}{y} $ <br\/> Suy ra: $ y = \\dfrac{1.48}{60} = 0,8 $ <br\/> V\u1eady trong 1 ph\u00fat \u0111o\u00e0n t\u00e0u \u0111i \u0111\u01b0\u1ee3c 0,8 km = 800 m\u00e9t <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":586},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" <span class='basic_left'> Tr\u00ean m\u1ed9t chi\u1ebfc \u0111\u1ed3ng h\u1ed3, khi kim gi\u1edd quay \u0111\u00fang 3 v\u00f2ng th\u00ec s\u1ed1 v\u00f2ng kim ph\u00fat quay \u0111\u01b0\u1ee3c l\u00e0: <\/span>","select":["A. 15 v\u00f2ng ","B. 36 v\u00f2ng ","C. 180 v\u00f2ng","D. 12 v\u00f2ng "],"hint":"L\u1eadp c\u00e1c t\u1ec9 s\u1ed1 t\u01b0\u01a1ng \u1ee9ng c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng. ","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\/> Kim gi\u1edd $ \\qquad$ Kim ph\u00fat <br\/> 1 v\u00f2ng $\\hspace{1cm}$ 12 v\u00f2ng <br\/> 3 v\u00f2ng $\\hspace{1cm}$ $y$ v\u00f2ng ? <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <span class='basic_left'> Ta c\u00f3: Khi kim gi\u1edd quay 1 v\u00f2ng th\u00ec kim ph\u00fat quay \u0111\u01b0\u1ee3c 12 v\u00f2ng. <br\/> V\u00ec s\u1ed1 v\u00f2ng quay c\u1ee7a kim gi\u1edd v\u00e0 kim ph\u00fat l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn. <br\/> N\u00ean theo t\u00ednh ch\u1ea5t c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn ta c\u00f3: $ \\dfrac{1}{3} = \\dfrac{12}{y} $ <br\/> Suy ra: $ y = \\dfrac{3.12}{1} = 36 $ <br\/> V\u1eady khi kim gi\u1edd quay \u0111\u00fang 3 v\u00f2ng th\u00ec kim ph\u00fat quay \u0111\u01b0\u1ee3c 36 v\u00f2ng. <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":587},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho bi\u1ebft $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $y$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 $a_{1}$ v\u00e0 $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 $a_{2}$. <br\/> $y$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0: <\/span>","select":["A. $a_{1}a_{2}$ ","B. $a_{1}+a_{2}$ ","C. $\\dfrac{a_{2}}{a_{1}} $ ","D. $\\dfrac{a_{1}}{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\/> Ta c\u00f3 $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $y$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 $a_{1}$ n\u00ean $x = a_{1}y$ ($a_{1}$ l\u00e0 h\u1eb1ng s\u1ed1 kh\u00e1c 0) <br\/> $\\Rightarrow y = \\dfrac{1}{a_{1}}.x $ <br\/> M\u00e0 $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $a_{2}$ n\u00ean $ x = a_{2}z$ ($a_{2}$ l\u00e0 h\u1eb1ng s\u1ed1 kh\u00e1c 0) <br\/> Do \u0111\u00f3 $y = \\dfrac{1}{a_{1}}.x = \\dfrac{1}{a_{1}}.(a_{2}z) = \\dfrac{a_{2}}{a_{1}}z $ <br\/> V\u00ec $a_{1}, a_{2}$ l\u00e0 c\u00e1c h\u1eb1ng s\u1ed1 kh\u00e1c 0 n\u00ean $ \\dfrac{a_{2}}{a_{1}} $ c\u0169ng l\u00e0 h\u1eb1ng s\u1ed1 kh\u00e1c 0. <br\/> V\u00e2y $y$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 $\\dfrac{a_{2}}{a_{1}} $ . <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":588},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho bi\u1ebft \u0111\u1ea1i l\u01b0\u1ee3ng $y$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $x$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k = \\dfrac{-2}{5} $. C\u1eb7p gi\u00e1 tr\u1ecb n\u00e0o d\u01b0\u1edbi \u0111\u00e2y l\u00e0 c\u1eb7p gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng n\u00f3i tr\u00ean? <\/span> ","select":["A. $x = -4; y = 10$ ","B. $x = 10; y = -4$ "],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> - \u0110\u1ea1i l\u01b0\u1ee3ng $y$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $x$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$ n\u00ean $ y = kx$ <br\/> - T\u00ecm $y$ theo c\u00f4ng th\u1ee9c $ y = kx $. <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/><span class='basic_left'> V\u00ec $y$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $x$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $ \\dfrac{-2}{5} $ n\u00ean $ y = \\dfrac{-2}{5}x $ <br\/> Khi $x = -4$ th\u00ec $y = \\dfrac{-2}{5}.(-4) = 1,6 \\neq 10 $ <br\/> V\u1eady $x = -4; y = 10$ kh\u00f4ng ph\u1ea3i l\u00e0 c\u1eb7p gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng n\u00f3i tr\u00ean. <br\/> Khi $x = 10$ th\u00ec $y = \\dfrac{-2}{5}.10 = -4 $ <br\/> V\u1eady $x = 10; y = -4$ l\u00e0 c\u1eb7p gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng n\u00f3i tr\u00ean.<br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":589},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<span class='basic_left'> Cho bi\u1ebft $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $y$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 0,8 v\u00e0 $y$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 5. <br\/> $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0: <\/span>","select":["A. 6,25 ","B. 0,16 ","C. 4 ","D. 5,8 "],"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\/> $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $y$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 0,8 n\u00ean $x = 0,8y$ <br\/> $y$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 5 n\u00ean $ y = 5z$ <br\/> Do \u0111\u00f3 $x = 0,8.(5z) = (0,8.5)z = 4z$ <br\/> V\u1eady $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 l\u00e0 4. <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":590},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":" Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn, bi\u1ebft r\u1eb1ng khi $x$ = -3 th\u00ec $ y $ = -6 <br\/> C\u1eb7p gi\u00e1 tr\u1ecb $(x; y)$ \u1edf c\u1ed9t n\u00e0o sau \u0111\u00e2y kh\u00f4ng th\u1ecfa m\u00e3n? <table> <tr> <td>C\u1ed9t<\/td><td>1<\/td><td>2<\/td><td>3<\/td><td>4<\/td> <\/tr><tr> <td>$x$<\/td><td>-4<\/td><td>-3<\/td><td>1<\/td><td>2<\/td> <\/tr><tr> <td>$y$<\/td><td>-8<\/td><td>-6<\/td><td>2<\/td><td>1<\/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\/> B\u01b0\u1edbc 1: X\u00e1c \u0111\u1ecbnh h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$ gi\u1eefa $y$ v\u00e0 $x$; $k = \\dfrac{y}{x}$ <br\/> B\u01b0\u1edbc 2: T\u00ecm $y$ theo c\u00f4ng th\u1ee9c $ y = kx $. <\/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\/> $k = \\dfrac{y}{x} = \\dfrac{-6}{-3} = 2 $ <br\/> Suy ra: $ y_{1} = k.x_{1} = 2.(-4) = -8; \\\\ y_{2} = k.x_{2} = 2.(-3) = -6; \\\\ y_{3} = k.x_{3} = 2.1 = 2 ;\\\\ y_{4} = k.x_{4} = 2.2 = 4$ <br\/> Suy ra c\u1ed9t sai l\u00e0 4. <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span><\/span> ","column":2}]}],"id_ques":591},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn. <table> <tr> <td>$x$<\/td><td>-5<\/td><td>-3<\/td><td>2<\/td><td>$x_{4}$<\/td><td>$x_{5}$<\/td> <\/tr><tr> <td>$y$<\/td><td>10<\/td><td>$y_{2}$ <\/td><td>$y_{3}$<\/td><td>-8<\/td><td>-12<\/td> <\/tr> <\/table> \u0110\u00e1p \u00e1n n\u00e0o kh\u00f4ng \u0111\u00fang? ","select":["A. $ y_{2} = 6 $ ","B. $ y_{3} = -4 $ ","C. $ x_{4} = -4 $ ","D. $ x_{5} = 6 $ "],"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 $k$ gi\u1eefa $y$ v\u00e0 $x$; $k = \\dfrac{y}{x}$ <br\/> B\u01b0\u1edbc 2: T\u00ecm $y$ theo c\u00f4ng th\u1ee9c $ y = kx $. <br\/> $ \\quad$ T\u00ecm $x$ theo c\u00f4ng th\u1ee9c $ x = \\dfrac{y}{k} $ <\/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\/> $k = \\dfrac{y_{1}}{x_{1}} = \\dfrac{10}{-5} = -2 $ <br\/> Suy ra: $ y_{2} = k.x_{2} = (-2).(-3) = 6; \\\\ y_{3} = k.x_{3} = (-2).2 = -4 ;\\\\ x_{4} = \\dfrac{y_{4}}{k} = \\dfrac{-8}{-2} = 4 \\\\ x_{5} = \\dfrac{y_{5}}{k} = \\dfrac{-12}{-2} = 6 $ <br\/> \u0110\u00e1p \u00e1n kh\u00f4ng \u0111\u00fang l\u00e0 C. $ x_{4} = -4 $<br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":592},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn. <table> <tr> <td>$x$<\/td><td>-6<\/td><td>-3<\/td><td>1<\/td><td>2<\/td><td>9<\/td> <\/tr><tr> <td>$y$<\/td><td>2<\/td><td>$y_{2}$ <\/td><td>$y_{3}$<\/td><td>$y_{4}$<\/td><td>$y_{5}$<\/td> <\/tr> <\/table> \u0110\u00e1p \u00e1n n\u00e0o kh\u00f4ng \u0111\u00fang? ","select":["A. $ y_{2} = 1 $ ","B. $ y_{3} = -3 $ ","C. $ y_{4} = \\dfrac{-2}{3} $ ","D. $ y_{5} = -3 $ "],"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 $k$ gi\u1eefa $y$ v\u00e0 $x$; $k = \\dfrac{y}{x}$ <br\/> B\u01b0\u1edbc 2: T\u00ecm $y$ theo c\u00f4ng th\u1ee9c $ y = kx $. <\/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\/> $k = \\dfrac{y_{1}}{x_{1}} = \\dfrac{2}{-6} = \\dfrac{-1}{3} $ <br\/> Suy ra: $ y_{2} = k.x_{2} = \\dfrac{-1}{3}.(-3) = 1; \\\\ y_{3} = k.x_{3} = \\dfrac{-1}{3}.1 = \\dfrac{-1}{3} ;\\\\ y_{4} = k.x_{4} = \\dfrac{-1}{3}.2 = \\dfrac{-2}{3} ; \\\\ y_{5} = k.x_{5} = \\dfrac{-1}{3}.9 = -3 $ <br\/> \u0110\u00e1p \u00e1n kh\u00f4ng \u0111\u00fang l\u00e0 B. $ y_{3} = -3 $ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":593},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" <table> <tr> <td>$x$<\/td><td>3<\/td><td>4<\/td><td>5<\/td><td>6<\/td><td>7<\/td> <\/tr><tr> <td>$y$<\/td><td>9<\/td><td>$y_{2}$ <\/td><td>$y_{3}$<\/td><td>$y_{4}$<\/td><td>$y_{5}$<\/td> <\/tr> <\/table> Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn. Khi \u0111\u00f3: ","select":["A. $ y_{2} = 8 $ ","B. $ y_{2} = 10 $ ","C. $ y_{3} = 15 $ ","D. $ y_{5} = 14 $ "],"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 $k$ gi\u1eefa $y$ v\u00e0 $x$; $k = \\dfrac{y}{x}$ <br\/> B\u01b0\u1edbc 2: T\u00ecm $y$ theo c\u00f4ng th\u1ee9c $ y = kx $. <\/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\/> $k = \\dfrac{y_{1}}{x_{1}} = \\dfrac{9}{3} = 3 $ <br\/> Suy ra: $y_{2} = k.x_{2} = 3.4 = 12; \\\\ y_{3} = k.x_{3} = 3.5 = 15 \\\\ y_{4} = k.x_{4} = 3.6 = 18 \\\\ y_{5} = k.x_{5} = 3.7 = 21 $ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":594},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn v\u00e0 khi $x$ = 0,25 th\u00ec $y$ = 4. T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a $x$ khi $y$ b\u1eb1ng $\\dfrac{-2}{3} $. ","select":["A. $\\dfrac{-32}{3} $ ","B. $\\dfrac{1}{24} $ ","C. $\\dfrac{-1}{24} $ ","D. $\\dfrac{-17}{6} $ "],"hint":"- T\u00ecm h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$. <br\/> - Thay v\u00e0o c\u00f4ng th\u1ee9c r\u1ed3i t\u00ecm $x$.","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 $k$ gi\u1eefa $y$ v\u00e0 $x$; $k = \\dfrac{y}{x}$ <br\/> B\u01b0\u1edbc 2: T\u00ecm $x$ theo c\u00f4ng th\u1ee9c $x = \\dfrac{y}{k} $. <\/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 $y = kx$; ($k$ l\u00e0 h\u1eb1ng s\u1ed1, $k \\neq 0$) <br\/> Theo \u0111i\u1ec1u ki\u1ec7n $x$ = 0,25 th\u00ec $y$ = 4 n\u00ean thay v\u00e0o ta t\u00ednh \u0111\u01b0\u1ee3c : <br\/> $k = \\dfrac{4}{0,25} = 16 $ <br\/> Do \u0111\u00f3, khi $y = \\dfrac{-2}{3} $ th\u00ec $x = \\dfrac{-2}{3} : 16 = \\dfrac{-1}{24} $ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":595},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":" Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn v\u00e0 khi $x$ = 3 th\u00ec $y$ = 6. T\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a $y$ khi $x$ b\u1eb1ng $\\dfrac{-3}{2} .$ ","select":["A. 3 ","B. -3 ","C. $\\dfrac{-3}{4} $ ","D. $\\dfrac{3}{4} $ "],"hint":"- T\u00ecm h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$. <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 $k$ gi\u1eefa $y$ v\u00e0 $x$; $k = \\dfrac{y}{x}$ <br\/> B\u01b0\u1edbc 2: T\u00ecm $y$ theo c\u00f4ng th\u1ee9c $ y = kx $. <\/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 $y = kx$; ($k$ l\u00e0 h\u1eb1ng s\u1ed1, $k \\neq 0$) <br\/> v\u00e0 theo \u0111i\u1ec1u ki\u1ec7n $x$ = 3 th\u00ec $y$ = 6 <br\/> N\u00ean thay v\u00e0o ta t\u00ednh \u0111\u01b0\u1ee3c: <br\/> $ k = \\dfrac{6}{3} = 2 $ <br\/> Do \u0111\u00f3, khi $x = \\dfrac{-3}{2}$ th\u00ec $y = 2.\\dfrac{-3}{2} = -3 $ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":596},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" Cho $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn v\u00e0 khi $x$ = 0,25 th\u00ec $y$ = 4. H\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$ c\u1ee7a $y$ \u0111\u1ed1i v\u1edbi $x$ l\u00e0: ","select":["A. 16 ","B. 0,0625 ","C. 4,25 ","D. 3,75 "],"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 $k$ gi\u1eefa $y$ v\u00e0 $x$; $k = \\dfrac{y}{x}$ <\/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 thu\u1eadn n\u00ean $y = kx$; ($k$ l\u00e0 h\u1eb1ng s\u1ed1, $k \\neq 0$) (1) <br\/> Theo \u0111i\u1ec1u ki\u1ec7n $x = 0,25$ th\u00ec $y = 4$ <br\/> N\u00ean thay $x = 0,25$ v\u00e0 $y = 4 $v\u00e0o (1) ta t\u00ednh \u0111\u01b0\u1ee3c: <br\/> $k = \\dfrac{4}{0,25} = 16 $ <br\/><br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":2}]}],"id_ques":597},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":" S\u1ed1 \u0111o c\u00e1c g\u00f3c $ \\widehat{A}, \\widehat{B}, \\widehat{C} $ c\u1ee7a $\\triangle ABC $ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi 2, 3, 4. H\u00e3y t\u00ednh s\u1ed1 \u0111o m\u1ed7i g\u00f3c c\u1ee7a tam gi\u00e1c \u0111\u00f3? ","select":["A. $40^{0}, 60^{0}, 80^{0} $ ","B. $20^{0}, 60^{0}, 100^{0} $ ","C. $30^{0}, 50^{0}, 90^{0} $ ","D. M\u1ed9t k\u1ebft qu\u1ea3 kh\u00e1c "],"hint":"\u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau. <br\/> C\u00f3: T\u1ed5ng s\u1ed1 \u0111o ba g\u00f3c c\u1ee7a tam gi\u00e1c b\u1eb1ng $180^{0}.$","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}{a} = \\dfrac{y}{b} = \\dfrac{z}{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 $x, y, z$. <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <span class='basic_left'> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $ \\dfrac{\\widehat{A}}{2} = \\dfrac{\\widehat{B}}{3} = \\dfrac{\\widehat{C}}{4}$ v\u00e0 $ \\widehat{A}+\\widehat{B}+\\widehat{C} = 180^{0}$ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $ \\dfrac{\\widehat{A}}{2} = \\dfrac{\\widehat{B}}{3} = \\dfrac{\\widehat{C}}{4} = \\dfrac{\\widehat{A}+\\widehat{B}+\\widehat{C}}{2+3+4} = \\dfrac{180^{0}}{9} = 20^{0} $ <br\/> Do \u0111\u00f3: $ \\widehat{A} = 2.20^{0} = 40^{0} \\\\ \\widehat{B} = 3.20^{0} = 60^{0} \\\\ \\widehat{C} = 4.20^{0} = 80^{0}$ <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":2}]}],"id_ques":598},{"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":[[["45"]]],"list":[{"point":5,"width":50,"type_input":"","ques":" <span class='basic_left'>\u0110\u1ed9 d\u00e0i c\u00e1c c\u1ea1nh c\u1ee7a m\u1ed9t tam gi\u00e1c t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi 4, 7, 9. Bi\u1ebft c\u1ea1nh nh\u1ecf nh\u1ea5t d\u00e0i 20 cm. T\u00ednh \u0111\u1ed9 d\u00e0i c\u1ee7a c\u1ea1nh l\u1edbn nh\u1ea5t. <\/span> <br\/> \u0110\u00e1p s\u1ed1: $\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}$ cm","hint":"L\u1eadp c\u00e1c t\u1ec9 s\u1ed1 t\u01b0\u01a1ng \u1ee9ng c\u1ee7a hai \u0111\u1ea1i l\u01b0\u1ee3ng. ","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\/> <span class='basic_left'> G\u1ecdi \u0111\u1ed9 d\u00e0i c\u00e1c c\u1ea1nh c\u1ee7a tam gi\u00e1c l\u1ea7n l\u01b0\u1ee3t l\u00e0: $x, y, z$ (cm) <br\/> Theo \u0111\u1ec1 b\u00e0i, ta c\u00f3: $\\dfrac{x}{4} = \\dfrac{y}{7} = \\dfrac{z}{9}$ <br\/> Do \u0111\u00f3: x l\u00e0 \u0111\u1ed9 d\u00e0i c\u1ea1nh nh\u1ecf nh\u1ea5t, y l\u00e0 \u0111\u1ed9 d\u00e0i c\u1ea1nh l\u1edbn nh\u1ea5t. <br\/> Khi $x = 20$ th\u00ec ta c\u00f3: $\\dfrac{20}{4} = \\dfrac{z}{9} $ <br\/> Suy ra: $z = \\dfrac{20.9}{4} = 45 $ <br\/> V\u1eady \u0111\u1ed9 d\u00e0i c\u1ea1nh l\u1edbn nh\u1ea5t l\u00e0 45 cm. <br\/><span class='basic_pink'> \u0110\u00e1p s\u1ed1 l\u00e0 45. <\/span><\/span> "}]}],"id_ques":599},{"time":24,"part":[{"title":"L\u1ef1a \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":" <span class='basic_left'> S\u1ed1 h\u1ecdc sinh m\u1ed7i kh\u1ed1i 6, 7, 8 t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi 13, 10, 12. S\u1ed1 h\u1ecdc sinh kh\u1ed1i 6 nhi\u1ec1u h\u01a1n s\u1ed1 h\u1ecdc sinh kh\u1ed1i 7 l\u00e0 60 h\u1ecdc sinh. S\u1ed1 h\u1ecdc sinh kh\u1ed1i 8 l\u00e0: <\/span>","select":["A. 260 h\u1ecdc sinh ","B. 200 h\u1ecdc sinh ","C. 240 h\u1ecdc sinh ","D. 220 h\u1ecdc sinh "],"hint":"\u0110\u1eb7t \u1ea9n ph\u1ee5 r\u1ed3i \u00e1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau.","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 c\u1ee7a d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau \u0111\u1ec3 t\u00ecm $x, y, z$. <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span> <br\/> <span class='basic_left'> G\u1ecdi s\u1ed1 h\u1ecdc sinh kh\u1ed1i 6, 7, 8 l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y, z$ (h\u1ecdc sinh). <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $ \\dfrac{x}{13} = \\dfrac{y}{10} = \\dfrac{z}{12} $ v\u00e0 $ x - y = 60 $ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $ \\dfrac{x}{13} = \\dfrac{y}{10} = \\dfrac{z}{12} = \\dfrac{x-y}{13-10} = \\dfrac{60}{3} = 20 $ <br\/> Do \u0111\u00f3: $x = 13.20 = 260 \\\\ y = 10.20 = 200 \\\\ z = 12.20 = 240 $ <br\/> V\u1eady s\u1ed1 h\u1ecdc sinh kh\u1ed1i 8 l\u00e0 240 h\u1ecdc sinh. <br\/><span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":600}],"lesson":{"save":0,"level":2}}