{"segment":[{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":10,"ques":"Cho bi\u1ebft \u0111\u1ea1i l\u01b0\u1ee3ng $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $y$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$. \u0110\u1ea1i l\u01b0\u1ee3ng $y$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$. Khi \u0111\u00f3: ","select":["A. \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 $k$. ","B. \u0110\u1ea1i l\u01b0\u1ee3ng $x$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$. ","C. \u0110\u1ea1i l\u01b0\u1ee3ng $x$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $2k$. ","D. \u0110\u1ea1i l\u01b0\u1ee3ng $x$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k^{2} $. "],"explain":"<span class='basic_left'> \u0110\u1ea1i l\u01b0\u1ee3ng $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $y$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$ th\u00ec \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 $\\dfrac{1}{k} \\Rightarrow A $ Sai. <br\/> Ta c\u00f3: \u0111\u1ea1i l\u01b0\u1ee3ng $x$ t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $y$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$ n\u00ean $x = ky (1)$ <br\/> \u0110\u1ea1i l\u01b0\u1ee3ng $y$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k$ n\u00ean $y = \\dfrac{k}{z} \\Rightarrow z = \\dfrac{k}{y} (2) $ <br\/> T\u1eeb (1) v\u00e0 (2) ta c\u00f3: $x.z = ky. \\dfrac{k}{y} = k^{2} $ <br\/> Do \u0111\u00f3 \u0111\u1ea1i l\u01b0\u1ee3ng $x$ t\u1ec9 l\u1ec7 ngh\u1ecbch v\u1edbi \u0111\u1ea1i l\u01b0\u1ee3ng $z$ theo h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7 $k^{2} $ <br\/> V\u1eady \u0111\u00e1p \u00e1n D \u0111\u00fang; \u0111\u00e1p \u00e1n B, C Sai. <br\/><br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span>","column":1}]}],"id_ques":851},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":"<span class='basic_left'>M\u1ed9t \u00f4 t\u00f4 \u0111i t\u1eeb A \u0111\u1ebfn B v\u1edbi v\u1eadn t\u1ed1c 48 km\/h. L\u00fac v\u1ec1 xe \u0111i qu\u00e3ng \u0111\u01b0\u1eddng BA v\u1edbi v\u1eadn t\u1ed1c 42 km\/h. Bi\u1ebft th\u1eddi gian c\u1ea3 \u0111i l\u1eabn v\u1ec1 l\u00e0 7 gi\u1edd 30 ph\u00fat. T\u00ednh \u0111\u1ed9 d\u00e0i qu\u00e3ng \u0111\u01b0\u1eddng AB. <\/span> ","select":["A. 192 km ","B. 168 km ","C. 336 km ","D. 360 km "],"explain":"<span class='basic_left'> \u0110\u1ed5i: 7 gi\u1edd 30 ph\u00fat = 7,5 gi\u1edd. <br\/> G\u1ecdi th\u1eddi gian l\u00fac xe \u0111i t\u1eeb A \u0111\u1ebfn B v\u00e0 t\u1eeb B v\u1ec1 A l\u1ea7n l\u01b0\u1ee3t l\u00e0 $t_{1}, t_{2} $ (gi\u1edd, $t_{1}, t_{2} > 0$ ) <br\/> V\u1eadn t\u1ed1c l\u00fac xe \u0111i t\u1eeb A \u0111\u1ebfn B v\u00e0 t\u1eeb B v\u1ec1 A l\u1ea7n l\u01b0\u1ee3t l\u00e0 $v_{1}, v_{2} $ <br\/> Theo b\u00e0i c\u00f3: $t_{1} + t_{2} = 7, 5 \\\\ v_{1} = 48 , v_{2} = 42 $ <br\/> V\u00ec th\u1eddi gian v\u00e0 v\u1eadn t\u1ed1c \u0111i c\u00f9ng m\u1ed9t qu\u00e3ng \u0111\u01b0\u1eddng l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch, n\u00ean ta c\u00f3: <br\/> $\\begin{aligned}& \\dfrac{{{t}_{1}}}{{{t}_{2}}}=\\dfrac{{{v}_{2}}}{{{v}_{1}}}=\\dfrac{42}{48}=\\dfrac{7}{8} \\\\ & \\Rightarrow \\dfrac{{{t}_{1}}}{7}=\\dfrac{{{t}_{2}}}{8}=\\dfrac{{{t}_{1}}+{{t}_{2}}}{7+8}=\\dfrac{7,5}{15}=0,5 \\\\ & \\Rightarrow \\left\\{\\begin{aligned} & {{t}_{1}}=7.0,5=3,5 \\\\ & {{t}_{2}}=8.0,5=4 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <br\/> \u0110\u1ed9 d\u00e0i qu\u00e3ng \u0111\u01b0\u1eddng AB l\u00e0: $t_{1}.v_{1} = 3,5.48 = 168 (km) $ <br\/><br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span>","column":2}]}],"id_ques":852},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":10,"ques":"<span class='basic_left'>Hai xe m\u00e1y c\u00f9ng \u0111i t\u1eeb A \u0111\u1ebfn B. Xe th\u1ee9 I \u0111i h\u1ebft 1 gi\u1edd 20 ph\u00fat, xe th\u1ee9 II \u0111i h\u1ebft 1 gi\u1edd 30 ph\u00fat. T\u00ecm v\u1eadn t\u1ed1c trung b\u00ecnh m\u1ed7i xe. Bi\u1ebft r\u1eb1ng trung b\u00ecnh m\u1ed7i ph\u00fat xe th\u1ee9 I \u0111i nhanh h\u01a1n xe th\u1ee9 II l\u00e0 100m. <\/span> ","select":["A. 990, 880 (m\/ph\u00fat) ","B. 950, 850 (m\/ph\u00fat) ","C. 700, 900 (m\/ph\u00fat) ","D. 900, 800 (m\/ph\u00fat) "],"explain":"<span class='basic_left'>\u0110\u1ed5i: 1 gi\u1edd 20 ph\u00fat = 80 ph\u00fat; 1 gi\u1edd 30 ph\u00fat = 90 ph\u00fat <br\/> G\u1ecdi $v_{1}, v_{2} $ l\u1ea7n l\u01b0\u1ee3t l\u00e0 v\u1eadn t\u1ed1c c\u1ee7a xe th\u1ee9 I v\u00e0 xe th\u1ee9 II.<br\/> Theo \u0111\u1ea7u b\u00e0i ta c\u00f3: $v_{1} - v_{2} = 100 $ <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 ta c\u00f3: $\\dfrac{{{v}_{1}}}{{{v}_{2}}}=\\dfrac{90}{80}$ <br\/> Do \u0111\u00f3: $\\begin{aligned}& \\frac{{{v}_{1}}}{90}=\\frac{{{v}_{2}}}{80}=\\dfrac{{{v}_{1}}-{{v}_{2}}}{90-80}=\\dfrac{100}{10}=10 \\\\& \\Rightarrow \\left\\{ \\begin{aligned}& {{v}_{1}}=90.10=900 \\\\ & {{v}_{2}}=80.10=800 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <br\/> V\u1eadn t\u1ed1c trung b\u00ecnh xe th\u1ee9 I, II l\u1ea7n l\u01b0\u1ee3t l\u00e0: 900, 800 (m\/ph\u00fat) <br\/><br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span>","column":2}]}],"id_ques":853},{"time":14,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["8"],["7"],["-6"],["7"]]],"list":[{"point":10,"width":50,"ques":"<span class='basic_left'>Gi\u1ea3 s\u1eed $x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn, $x_{1}, x_{2} $ l\u00e0 hai gi\u00e1 tr\u1ecb kh\u00e1c nhau c\u1ee7a $x$; $y_{1}, y_{2} $ l\u00e0 hai gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a $y$. T\u00ednh $x_{1}, y_{1} $ bi\u1ebft $y_{1} - x_{1} = -2, x_{2} = -4, y_{2} = 3 $<\/span><br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> $x_{1} =$ <div class=\"frac123\"><div class=\"ts\">_input_<\/div><div class=\"ms\">_input_<\/div><\/div>; $\\qquad y_{1} = $ <div class=\"frac123\"><div class=\"ts\">_input_<\/div><div class=\"ms\">_input_<\/div><\/div>","explain":"$x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 thu\u1eadn n\u00ean $k = \\dfrac{y_{1}}{x_{1}} = \\dfrac{y_{2}}{x_{2}} $ <br\/> Do \u0111\u00f3: $ \\dfrac{{{y}_{1}}}{{{y}_{2}}}=\\dfrac{{{x}_{1}}}{{{x}_{2}}}=\\dfrac{{{y}_{1}}-{{x}_{1}}}{{{y}_{2}}-{{x}_{2}}}=\\dfrac{-2}{3-(-4)}=\\dfrac{-2}{7} $ <br\/> $\\Rightarrow $$ {{x}_{1}}=\\dfrac{-2}{7}.{{x}_{2}}=\\dfrac{-2}{7}.(-4)=\\dfrac{8}{7} \\\\ {{y}_{1}}=\\dfrac{-2}{7}.{{y}_{2}}=\\dfrac{-2}{7}.3=\\dfrac{-6}{7} $"}]}],"id_ques":854},{"time":14,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["-6"],["-14"]]],"list":[{"point":10,"width":50,"ques":"<span class='basic_left'>Cho hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch $x$ v\u00e0 $y$, $x_{1}, x_{2} $ l\u00e0 hai gi\u00e1 tr\u1ecb c\u1ee7a $x$; $y_{1}, y_{2} $ l\u00e0 hai gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng c\u1ee7a $y$. Bi\u1ebft $x_{2} = 3, y_{1} = 7 $ v\u00e0 $2x_{1} - 3y_{2} = 30 $. T\u00ednh $x_{1}, y_{2} $ <br\/><b> \u0110\u00e1p s\u1ed1: <\/b> $x_{1} =$ _input_; $\\qquad y_{2} = $ _input_ <\/span>","explain":"$x$ v\u00e0 $y$ l\u00e0 hai \u0111\u1ea1i l\u01b0\u1ee3ng t\u1ec9 l\u1ec7 ngh\u1ecbch n\u00ean $a = x_{1}y_{1} = x_{2}y_{2} $ <br\/> Do \u0111\u00f3: $ \\dfrac{{{x}_{1}}}{{{x}_{2}}}=\\dfrac{{{y}_{2}}}{{{y}_{1}}}=\\dfrac{2{{x}_{1}}}{2{{x}_{2}}}=\\dfrac{3{{y}_{2}}}{3{{y}_{1}}}=\\dfrac{2{{x}_{1}}-3{{y}_{2}}}{2{{x}_{2}}-3{{y}_{1}}}(1)$ <br\/> V\u00ec $ x_{2} = 3, y_{1} = 7$ v\u00e0 $2x_{1} - 3y_{2} = 30 $ n\u00ean t\u1eeb (1) ta c\u00f3: <br\/> $\\begin{aligned} & \\dfrac{{{x}_{1}}}{3}=\\dfrac{{{y}_{2}}}{7}=\\dfrac{2{{x}_{1}}-3{{y}_{2}}}{2.3-3.7}=\\dfrac{30}{-15}=-2 \\\\ & \\Rightarrow \\left\\{ \\begin{aligned} & {{x}_{1}}=3.(-2)=-6 \\\\ & {{y}_{2}}=7.(-2)=-14 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$"}]}],"id_ques":855},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["7"],["18"],["3"]]],"list":[{"point":10,"width":20,"content":"","type_input":"","ques":"Cho h\u00e0m s\u1ed1: $y=f(x)=\\begin{cases}-3x + 1 &n\u1ebfu \\quad x < -1\\dfrac{1}{2} \\\\ 3&n\u1ebfu -1\\dfrac{1}{2} \\leq x < \\dfrac{1}{2} \\\\ 5x +3 &n\u1ebfu \\quad x \\geq \\dfrac{1}{2} \\end{cases}$ <br\/><br\/> Khi \u0111\u00f3 $f(-2) = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\\\ f(3) = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\\\ f(0) = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} $ ","explain":"V\u00ec $-2 < -1\\dfrac{1}{2} $ n\u00ean $f(x) = -3x + 1 $ <br\/> $\\Rightarrow f(-2) = -3.(-2) + 1 = 6 + 1 = 7 $ <br\/> V\u00ec $3 > \\dfrac{1}{2} $ n\u00ean $f(x) = 5x + 3 $ <br\/> $\\Rightarrow f(3) = 5.3 + 3 = 18 $ <br\/> V\u00ec $ -1\\dfrac{1}{2} < 0 < \\dfrac{1}{2} $ n\u00ean $f(x) = 3 $ <br\/> $\\Rightarrow f(0) = 3 $ <br\/> <span class='basic_pink'>V\u1eady c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u1ea7n l\u01b0\u1ee3t l\u00e0 $ 7; 18; 3 $<\/span> "}]}],"id_ques":856},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":"H\u00ecnh sau l\u00e0 \u0111\u1ed3 th\u1ecb c\u1ee7a h\u00e0m s\u1ed1 $y = ax .$ H\u1ecfi h\u00e0m s\u1ed1 n\u00e0y \u0111\u01b0\u1ee3c cho b\u1edfi c\u00f4ng th\u1ee9c n\u00e0o? <br\/> <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/daiso/bai18/lv3/img\/D7B18-12.png' \/><\/center> ","select":["A. $y = \\dfrac{3}{2}x $","B. $y = \\dfrac{2}{3}x $ ","C. $y = x $ ","D. $y = 6x $ "],"explain":"\u0110\u1ed3 th\u1ecb h\u00e0m s\u1ed1 $y = ax$ l\u00e0 \u0111\u01b0\u1eddng th\u1eb3ng \u0111i qua g\u1ed1c t\u1ecda \u0111\u1ed9 v\u00e0 \u0111i\u1ec3m A(3; 2) <br\/> Do \u0111\u00f3 khi $x = 3$ th\u00ec $y = a.3 = 2 \\Rightarrow a = \\dfrac{2}{3}$ <br\/> H\u00e0m s\u1ed1 \u0111\u00f3 l\u00e0: $y = \\dfrac{2}{3}x $ <br\/><br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span>","column":2}]}],"id_ques":857},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":10,"ques":"\u0110\u1ed3 th\u1ecb c\u1ee7a h\u00e0m s\u1ed1 $y = ax$ \u0111i qua \u0111i\u1ec3m $M(-3; 4,5).$ H\u1ecfi $N(8; -12)$ c\u00f3 thu\u1ed9c \u0111\u1ed3 th\u1ecb c\u1ee7a h\u00e0m s\u1ed1 $y = ax$ kh\u00f4ng? ","select":["C\u00f3","kh\u00f4ng"],"explain":"Thay $x = -3; y = 4,5$ v\u00e0o h\u00e0m s\u1ed1 y = ax ta \u0111\u01b0\u1ee3c: <br\/> $4,5 = -3.a \\Rightarrow a = -1,5 $ <br\/> V\u1eady h\u00e0m s\u1ed1 \u0111\u00e3 cho l\u00e0 h\u00e0m s\u1ed1 $y = -1,5x$ <br\/> Thay $x = 8; y = -12$ v\u00e0o h\u00e0m s\u1ed1 $y = -1,5x $ ta \u0111\u01b0\u1ee3c m\u1ed9t \u0111\u1eb3ng th\u1ee9c \u0111\u00fang: <br\/> $-12 = -1,5.8$ <br\/> V\u1eady \u0111i\u1ec3m $N(8; -12)$ thu\u1ed9c \u0111\u1ed3 th\u1ecb c\u1ee7a h\u00e0m s\u1ed1 \u0111\u00e3 cho. <br\/><br\/> <span class='basic_pink'>\u0110\u00e1p \u00e1n l\u00e0 ''C\u00f3''. <\/span>","column":2}]}],"id_ques":858},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["55"]]],"list":[{"point":10,"width":20,"content":"","type_input":"","ques":"Chia s\u1ed1 M th\u00e0nh ba ph\u1ea7n t\u1ec9 l\u1ec7 thu\u1eadn v\u1edbi c\u00e1c s\u1ed1 5; 2; 4. Bi\u1ebft s\u1ed1 nh\u1ecf nh\u1ea5t b\u1eb1ng 10. T\u00ednh s\u1ed1 M. <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> $M = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}$","explain":"G\u1ecdi ba ph\u1ea7n \u0111\u00f3 l\u00e0 x, y, z. (x, y, z $\\geq 10 $) <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $\\dfrac{x}{5} = \\dfrac{y}{2} = \\dfrac{z}{4} $ <br\/> V\u00ec s\u1ed1 nh\u1ecf nh\u1ea5t b\u1eb1ng 10 n\u00ean y = 10. <br\/> Do v\u1eady: $\\dfrac{x}{5} = \\dfrac{10}{2} = \\dfrac{z}{4} = 5 $<br\/> $ \\Rightarrow $ $x = 5.5 = 25 \\\\ z = 4.5 = 20 $ <br\/> V\u1eady s\u1ed1 M b\u1eb1ng: 25 + 10 + 20 = 55 <br\/><br\/> <span class='basic_pink'>V\u1eady c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $ 55 $ <\/span> "}]}],"id_ques":859},{"time":24,"part":[{"title":"\u0110i\u1ec1n t\u1eeb th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["-2"],["-6"]]],"list":[{"point":10,"width":20,"content":"","type_input":"","ques":"X\u00e1c \u0111\u1ecbnh \u0111i\u1ec3m $M(x; y)$ tr\u00ean \u0111\u1ed3 th\u1ecb h\u00e0m s\u1ed1 $y = 3x$ bi\u1ebft: $x + 2y = -14$ <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> $M(\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}; \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}) $ ","explain":"Thay $y = 3x$ v\u00e0o \u0111\u1eb3ng th\u1ee9c $x + 2y = -14$ ta \u0111\u01b0\u1ee3c: <br\/> $x + 2.3x = -14 \\\\ \\Rightarrow 7x = -14 \\\\ \\Rightarrow x = -2 $ <br\/> V\u1edbi $x = -2$ th\u00ec $y = 3.(-2) = -6$ <br\/> Suy ra t\u1ecda \u0111\u1ed9 c\u1ee7a \u0111i\u1ec3m M l\u00e0 $M(-2; -6)$ <br\/> <span class='basic_pink'>V\u1eady c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u1ea7n l\u01b0\u1ee3t l\u00e0 $ -2; -6 $<\/span> "}]}],"id_ques":860}],"lesson":{"save":0,"level":3}}