{"segment":[{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["23"],["6"]]],"list":[{"width":50,"type_input":"","point":10,"ques":" T\u00ecm $x$ trong t\u1ec9 l\u1ec7 th\u1ee9c: $ \\dfrac{x-3}{5-x} = \\dfrac{5}{7} $ <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> $ x = \\dfrac{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}}{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}} $","hint":" \u00c1p d\u1ee5ng: $ \\dfrac{a}{b} = \\dfrac{c}{d} \\Leftrightarrow ad = bc $ ","explain":" \u0110i\u1ec1u ki\u1ec7n: $x\\neq 5$ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t c\u1ee7a t\u1ec9 l\u1ec7 th\u1ee9c ta c\u00f3: <br\/> $ \\dfrac{x-3}{5-x} = \\dfrac{5}{7} \\\\ \\Rightarrow 7.(x - 3) = 5.(5 - x) \\\\ \\Rightarrow 7x - 21 = 25 - 5x \\\\ \\Rightarrow 7x + 5x = 21 + 25 \\\\ \\Rightarrow 12x = 46 \\\\ \\Rightarrow x = \\dfrac{46}{12} = \\dfrac{23}{6} $ <br\/> <br\/> <span class='basic_pink'> V\u1eady gi\u00e1 tr\u1ecb c\u1ee7a x l\u00e0 $ \\dfrac{23}{6} $ <\/span><\/span>"}]}],"id_ques":541},{"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":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/daiso/bai11/lv3/img\/2.jpg'\/><\/center> T\u00ecm $x \\in \\mathbb{Q}$ bi\u1ebft: <br\/> $ \\dfrac{11}{12} - \\left( \\dfrac{2}{5} + x \\right) = \\dfrac{2}{3} $ ","select":["A. $ x = \\dfrac{3}{20}$","B. $x = \\dfrac{-3}{20}$","C. $x = \\dfrac{71}{60}$","D. $ x = \\dfrac{-71}{60} $"],"hint":"","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> B\u00e0i to\u00e1n t\u00ecm x <\/b> <br\/> B\u01b0\u1edbc 1. B\u1ecf d\u1ea5u ngo\u1eb7c. <br\/> B\u01b0\u1edbc 2. Chuy\u1ec3n c\u00e1c h\u1ea1ng t\u1eed ch\u1ee9a $x$ sang m\u1ed9t v\u1ebf, c\u00e1c h\u1eb1ng s\u1ed1 sang v\u1ebf kia. <br\/> B\u01b0\u1edbc 3. Thu g\u1ecdn v\u00e0 t\u00ecm $x$. <\/span> <br\/><br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> <br\/> Ta c\u00f3: $ \\dfrac{11}{12} - \\left( \\dfrac{2}{5} + x \\right) = \\dfrac{2}{3} \\\\ \\Rightarrow \\dfrac{11}{12} - \\dfrac{2}{5} - x = \\dfrac{2}{3} \\\\ \\Rightarrow \\dfrac{11}{12} - \\dfrac{2}{5} - \\dfrac{2}{3} = x \\\\ \\Rightarrow x = \\dfrac{55}{60} - \\dfrac{24}{60} - \\dfrac{40}{60} \\\\ \\Rightarrow x = \\dfrac{-9}{60} = \\dfrac{-3}{20}$ <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span> <br\/>","column":2}]}],"id_ques":542},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["3"]]],"list":[{"width":50,"content":"","type_input":"","point":10,"ques":" Th\u1ef1c hi\u1ec7n ph\u00e9p t\u00ednh: \\begin{align*} M = \\dfrac{14}{13} + \\dfrac{5}{6} + \\dfrac{3}{5} - \\dfrac{1}{13} + \\dfrac{1}{6} + \\dfrac{2}{5} = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\end{align*}","hint":"Nh\u00f3m s\u1ed1 h\u1ea1ng th\u00edch h\u1ee3p r\u1ed3i th\u1ef1c hi\u1ec7n ph\u00e9p t\u00ednh.","explain":"Ta c\u00f3: $ M = \\dfrac{14}{13} + \\dfrac{5}{6} + \\dfrac{3}{5} - \\dfrac{1}{13} + \\dfrac{1}{6} + \\dfrac{2}{5} \\\\ = \\left( \\dfrac{14}{13} - \\dfrac{1}{13} \\right) + \\left( \\dfrac{5}{6} + \\dfrac{1}{6} \\right) + \\left( \\dfrac{3}{5} + \\dfrac{2}{5} \\right) \\\\ = 1 + 1 +1 = 3 $<br\/> <br\/> <span class='basic_pink'> V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $3$ <\/span><\/span> <br\/>"}]}],"id_ques":543},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["7"],["3"]]],"list":[{"width":50,"content":"","type_input":"","point":10,"ques":" T\u00ecm $x \\notin \\lbrace 1;3;8;20\\rbrace$ bi\u1ebft: <br\/> $\\dfrac{2}{(x-1)(x-3)} + \\dfrac{5}{(x-3)(x-8)} $ $ + \\dfrac{12}{(x-8)(x-20)} - \\dfrac{1}{x-20} $ $ = \\dfrac{-3}{4}$ <br\/> <br\/> <b> \u0110\u00e1p s\u1ed1: <\/b> $ x = \\dfrac{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}}{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}}$","hint":"\u0110\u01b0a t\u1eed s\u1ed1 c\u1ee7a m\u1ed7i ph\u00e2n th\u1ee9c \u1edf v\u1ec1 tr\u00e1i th\u00e0nh hi\u1ec7u hai th\u1eeba s\u1ed1 \u1edf m\u1eabu r\u1ed3i r\u00fat g\u1ecdn.","explain":" <span class='basic_left'> VT = $ \\dfrac{2}{(x-1)(x-3)} + \\dfrac{5}{(x-3)(x-8)} $$+ \\dfrac{12}{(x-8)(x-20)} - \\dfrac{1}{x-20} $<br\/>$ = \\dfrac{(x-1)-(x-3)}{(x-3)(x-1)} $$+ \\dfrac{(x-3)-(x-8)}{(x-8)(x-3)} $$ + \\dfrac{(x-8)-(x-20)}{(x-20)(x-8)} $$- \\dfrac{1}{x-20} $ <br\/> $ = \\dfrac{(x-1)}{(x-3)(x-1)} $$- \\dfrac{(x-3)}{(x-3)(x-1)} $$ + \\dfrac{(x-3)}{(x-8)(x-3)} $$ - \\dfrac{(x-8)}{(x-8)(x-3)} $ <br\/> $ + \\dfrac{(x-8)}{(x-20)(x-8)} $$ - \\dfrac{(x-20)}{(x-20)(x-8)} $$ - \\dfrac{1}{x-20} $ <br\/> $ = \\dfrac{1}{x-3} - \\dfrac{1}{x-1} $$ + \\dfrac{1}{x-8} - \\dfrac{1}{x-3} $$ + \\dfrac{1}{x-20} - \\dfrac{1}{x-8} $$ - \\dfrac{1}{x-20} $ <br\/> $ = -\\dfrac{1}{x-1} $ <br\/> Suy ra $ -\\dfrac{1}{x-1} = -\\dfrac{3}{4} \\Rightarrow \\dfrac{1}{x-1} = \\dfrac{3}{4} $ <br\/> $ \\Rightarrow 4 = 3(x-1) \\Rightarrow 4 = 3x - 3 $ <br\/> $ \\Rightarrow 7 = 3x \\Rightarrow x = \\dfrac{7}{3} $<br\/> <br\/> <span class='basic_pink'> Gi\u00e1 tr\u1ecb c\u1ee7a x l\u00e0 $\\dfrac{7}{3}.$ <\/span><\/span> <br\/>"}]}],"id_ques":544},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n \u0111\u00fang v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["2016"],["2017"]]],"list":[{"width":50,"content":"","type_input":"","point":10,"ques":"Th\u1ef1c hi\u1ec7n ph\u00e9p t\u00ednh: $ Q = \\dfrac{1}{1.2} + \\dfrac{1}{2.3} + \\dfrac{1}{3.4} + ... + \\dfrac{1}{2016.2017} = \\dfrac{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}}{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}} $","hint":"\u00c1p d\u1ee5ng: $\\dfrac{1}{x(x+1)} = \\dfrac{1}{x} - \\dfrac{1}{x+1}$ ","explain":" <span class='basic_left'> Ta th\u1ea5y: <br\/> $ \\dfrac{1}{1.2} = 1 - \\dfrac{1}{2}; $<br\/> $ \\dfrac{1}{2.3} = \\dfrac{1}{2} - \\dfrac{1}{3}; $<br\/> $ \\dfrac{1}{3.4} = \\dfrac{1}{3} - \\dfrac{1}{4}$; <br\/> ... <br\/> $\\dfrac{1}{2016.2017} = \\dfrac{1}{2016} - \\dfrac{1}{2017} $ <br\/> <br\/> Suy ra: $ Q = 1 - \\dfrac{1}{2} + \\dfrac{1}{2} - \\dfrac{1}{3} + \\dfrac{1}{3} - \\dfrac{1}{4} $$+ ... + \\dfrac{1}{2016} - \\dfrac{1}{2017} $<br\/> $ \\qquad \\qquad = 1 - \\dfrac{1}{2017} = \\dfrac{2016}{2017} $ <br\/> <br\/> <span class='basic_pink'> Gi\u00e1 tr\u1ecb c\u1ee7a Q l\u00e0 $\\dfrac{2016}{2017}$ <\/span><\/span> <br\/>"}]}],"id_ques":545},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","content":"","correct":[[1]],"list":[{"point":10,"ques":" T\u00ecm s\u1ed1 nguy\u00ean $x$ bi\u1ebft: <br\/> $\\dfrac{\\vert x \\vert}{(a+3)(2-a)} = \\dfrac{1}{a+3} + \\dfrac{1}{2-a} $$ (a \\neq 2, a\\neq -3)$","select":["A. $x = \\pm 5$","B. $x = 5 $","C. $x = \\pm 1$","D. $ x = 1 $"],"hint":"Quy \u0111\u1ed3ng m\u1eabu s\u1ed1. ","explain":"Ta c\u00f3: $\\dfrac{\\vert x \\vert}{(a+3)(2-a)} = \\dfrac{1}{a+3} + \\dfrac{1}{2-a} (a \\neq 2, a\\neq 3) \\\\ \\dfrac{\\vert x \\vert }{(a+3)(2-a)} = \\dfrac{2-a+a+3}{(a+3)(2-a)} \\\\ \\dfrac{\\vert x \\vert }{(a+3)(2-a)} = \\dfrac{5}{(a+3)(2-a)}$ <br\/> Suy ra : $\\vert x \\vert = 5 \\\\ \\Rightarrow x = \\pm 5.$ <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> <br\/>","column":2}]}],"id_ques":546},{"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":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/daiso/bai11/lv3/img\/4.jpg'\/><\/center> Gi\u00e1 tr\u1ecb bi\u1ec3u th\u1ee9c $\\sqrt{\\dfrac{8^{10}+4^{10}}{8^{4}+4^{11}}} $ b\u1eb1ng: ","select":["A. 32 ","B. 16 ","C. $\\dfrac{\\sqrt{2}}{12}$","D. $\\dfrac{1}{12}$ "],"hint":"\u0110\u01b0a t\u1ea5t c\u1ea3 v\u1ec1 c\u01a1 s\u1ed1 2. ","explain":" Ta c\u00f3: $ \\sqrt{\\dfrac{8^{10}+4^{10}}{8^{4}+4^{11}}} = \\sqrt{\\dfrac{(2^{3})^{10}+(2^{2})^{10}}{(2^{3})^{4}+(2^{2})^{11}}} = \\sqrt{\\dfrac{2^{30}+2^{20}}{2^{12}+2^{22}}} $ <br\/> $ = \\sqrt{\\dfrac{2^{20}(2^{10}+1)}{2^{12}(1+2^{10})}} = \\sqrt{\\dfrac{2^{20}}{2^{12}}} $$= \\sqrt{2^{8}} = \\sqrt{(2^{4})^{2}} \\\\ = 2^{4} = 16 $ <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":547},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":10,"ques":" T\u00ecm $x$ bi\u1ebft: <br\/> $ x - 68 = \\left( 3\\dfrac{10}{11} - 4 \\right) $$: \\left(\\dfrac{2121}{2222} - 1 \\right) : \\left( \\dfrac{333333}{343434} - 1 \\right) $ ","select":["A. $x = -68$ ","B. $x = 0$","C. $x = 1$","D. $x = 10$ "],"hint":"C\u00f3: $\\dfrac{2121}{2222} = \\dfrac{21.101}{22.101} $ ","explain":" <span class='basic_left'> Ta c\u00f3: $ (x - 68) = \\left( 3\\dfrac{10}{11} - 4 \\right) : \\left(\\dfrac{2121}{2222} - 1 \\right) : $$ \\left( \\dfrac{333333}{343434} - 1 \\right) $ <br\/> $ \\Rightarrow x - 68 = \\left( \\dfrac{43}{11} - \\dfrac{44}{11} \\right) $$ : \\left(\\dfrac{21.101}{22.101} - 1 \\right) : \\left( \\dfrac{33.10101}{34.10101} - 1 \\right) $ <br\/> $ \\Rightarrow x - 68 = \\dfrac{-1}{11} : \\left( \\dfrac{21}{22} - 1 \\right) : \\left( \\dfrac{33}{34} - 1 \\right) $ <br\/> $ \\Rightarrow x - 68 = \\dfrac{-1}{11} : \\dfrac{-1}{22} : \\dfrac{-1}{34} $ <br\/> $ \\Rightarrow x - 68 = \\dfrac{-1}{11} . (-22) . (-34) = -68 $ <br\/> $ \\Rightarrow x - 68 = -68 $ <br\/> $\\Rightarrow x = 0 $ <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":548},{"time":24,"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 t\u1ea5m v\u1ea3i c\u00f3 chi\u1ec1u d\u00e0i t\u1ed5ng c\u1ed9ng 145m. N\u1ebfu c\u1eaft t\u1ea5m th\u1ee9 nh\u1ea5t \u0111i $\\dfrac{1}{2}$, t\u1ea5m th\u1ee9 hai \u0111i $\\dfrac{1}{3}$, t\u1ea5m th\u1ee9 ba \u0111i $\\dfrac{1}{4}$ chi\u1ec1u d\u00e0i m\u1ed7i t\u1ea5m th\u00ec chi\u1ec1u d\u00e0i c\u00f2n l\u1ea1i c\u1ee7a m\u1ed7i t\u1ea5m v\u1ea3i b\u1eb1ng nhau. T\u00ednh chi\u1ec1u d\u00e0i c\u1ee7a t\u1ea5m v\u1ea3i d\u00e0i nh\u1ea5t tr\u01b0\u1edbc khi c\u1eaft? <\/span>","select":["A. 40m ","B. 45m ","C. 60m ","D. 70m "],"hint":"\u0110\u1eb7t \u1ea9n ph\u1ee5 theo \u0111i\u1ec1u ki\u1ec7n b\u00e0i to\u00e1n. ","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. Sau \u0111\u00f3 t\u00ecm $x, y, z$ <br\/> <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> G\u1ecdi chi\u1ec1u d\u00e0i ba t\u1ea5m v\u1ea3i tr\u01b0\u1edbc khi c\u1eaft l\u1ea7n l\u01b0\u1ee3t l\u00e0 $x, y, z$(m) (x, y, z > 0) <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $x + y + z = 145$ <br\/> Sau khi c\u1eaft, t\u1ea5m th\u1ee9 nh\u1ea5t c\u00f2n $ \\dfrac{1}{2}x $, t\u1ea5m th\u1ee9 hai c\u00f2n $ \\dfrac{2}{3}y $, t\u1ea5m th\u1ee9 ba c\u00f2n $ \\dfrac{3}{4}z $ <br\/> V\u00ec s\u1ed1 m\u00e9t v\u1ea3i c\u00f2n l\u1ea1i c\u1ee7a m\u1ed7i t\u1ea5m b\u1eb1ng nhau n\u00ean ta c\u00f3: $\\dfrac{1}{2}x = \\dfrac{2}{3}y = \\dfrac{3}{4}z $ <br\/> hay $ \\dfrac{x}{12} = \\dfrac{y}{9} = \\dfrac{z}{8}$ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $ \\dfrac{x}{12} = \\dfrac{y}{9} = \\dfrac{z}{8} = \\dfrac{x+y+z}{12+9+8} = \\dfrac{145}{29} = 5 $ <br\/> Do \u0111\u00f3: $ x = 12 .5 = 60 \\\\ y = 9.5 = 45 \\\\ z = 8.5 = 40 $ <br\/> V\u1eady chi\u1ec1u d\u00e0i c\u1ee7a t\u1ea5m v\u1ea3i d\u00e0i nh\u1ea5t tr\u01b0\u1edbc khi c\u1eaft l\u00e0 60m. <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":2}]}],"id_ques":549},{"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":"T\u00ecm ba s\u1ed1 d\u01b0\u01a1ng, bi\u1ebft t\u1ed5ng c\u00e1c b\u00ecnh ph\u01b0\u01a1ng c\u1ee7a ch\u00fang b\u1eb1ng 181; s\u1ed1 th\u1ee9 hai b\u1eb1ng $\\dfrac{3}{4}$ s\u1ed1 th\u1ee9 nh\u1ea5t v\u00e0 b\u1eb1ng $\\dfrac{2}{3}$ s\u1ed1 th\u1ee9 ba? ","select":["A. 7, 6, 9 ","B. 8, 6, 9 ","C. 2, 3, 4","D. 5, 7, 9"],"hint":"\u0110\u1eb7t \u1ea9n ph\u1ee5 theo \u0111i\u1ec1u ki\u1ec7n b\u00e0i to\u00e1n ","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^{2}}{m^{2}} = \\dfrac{y^{2}}{n^{2}} = \\dfrac{z^{2}}{t^{2}}$, trong \u0111\u00f3 $ x^{2} + y^{2} + z^{2} = M $ <br\/> B\u01b0\u1edbc 2. Sau \u0111\u00f3 t\u00ecm $x^{2}, y^{2}, z^{2} $ <br\/> B\u01b0\u1edbc 3. Suy ra $x, y, z$ <br\/> <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> G\u1ecdi ba s\u1ed1 l\u1ea7n l\u01b0\u1ee3t l\u00e0 $a, b, c (a, b, c > 0)$ <br\/> Theo \u0111\u1ec1 b\u00e0i ta c\u00f3: $a^{2} + b^{2} + c^{2} = 181$ v\u00e0 $b = \\dfrac{3}{4}a = \\dfrac{2}{3}c $ <br\/> Suy ra: $ \\dfrac{3a}{4} = \\dfrac{b}{1} = \\dfrac{2c}{3} \\\\ \\Rightarrow \\dfrac{a}{8} = \\dfrac{b}{6} = \\dfrac{c}{9} \\\\ \\Rightarrow \\dfrac{a^{2}}{64} = \\dfrac{b^{2}}{36} = \\dfrac{c^{2}}{81} $ <br\/> \u00c1p d\u1ee5ng t\u00ednh ch\u1ea5t d\u00e3y t\u1ec9 s\u1ed1 b\u1eb1ng nhau ta c\u00f3: <br\/> $ \\dfrac{a^{2}}{64} = \\dfrac{b^{2}}{36} = \\dfrac{c^{2}}{81} = \\dfrac{a^{2} + b^{2} + c^{2}}{64+36+81} = \\dfrac{181}{181} = 1 $ <br\/> Do \u0111\u00f3: $ \\dfrac{a^{2}}{64} = 1 \\Rightarrow a^{2} = 64 \\Rightarrow a = \\pm 8 \\\\ \\dfrac{b^{2}}{36} = 1 \\Rightarrow b^{2} = 36 \\Rightarrow b = \\pm 6 \\\\ \\dfrac{c^{2}}{81} = 1 \\Rightarrow c^{2} = 81 \\Rightarrow c = \\pm 9 $ <br\/> V\u00ec a, b, c l\u00e0 s\u1ed1 d\u01b0\u01a1ng n\u00ean: a = 8; b = 6; c = 9 <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":550}],"lesson":{"save":0,"level":3}}