{"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":10,"ques":" So s\u00e1nh hai t\u1ed5ng A v\u00e0 B n\u1ebfu: <br\/> $A = \\sqrt{20+1} + \\sqrt{40+2} + \\sqrt{60+3}$ <br\/> v\u00e0 $B = (\\sqrt{1} + \\sqrt{2} + \\sqrt{3}) + $ $(\\sqrt{20} + \\sqrt{40} + \\sqrt{60}) $ ","select":["A. A < B ","B. A > B","C. A = B "],"hint":"Ta c\u00f3: $\\sqrt{20+1} < \\sqrt{20} + \\sqrt{1} $","explain":" <span class='basic_left'> Ta c\u00f3: $\\sqrt{20+1} = \\sqrt{21} < \\sqrt{25} = 5,$ <br\/> m\u00e0 $5 = 4 + 1 = \\sqrt{16} + \\sqrt{1} < \\sqrt{20} + \\sqrt{1} $ <br\/> $\\Rightarrow \\sqrt{20+1} < \\sqrt{20} + \\sqrt{1}$ <br\/> T\u01b0\u01a1ng t\u1ef1: $\\sqrt{40+2} < \\sqrt{40} + \\sqrt{2} \\\\ \\sqrt{60+3} < \\sqrt{60} + \\sqrt{3}$ <br\/> Suy ra $A = \\sqrt{20+1} + \\sqrt{40+2} + \\sqrt{60+3} \\\\ < \\sqrt{20} + \\sqrt{1} + \\sqrt{40} + \\sqrt{2} + \\sqrt{60} + \\sqrt{3} \\\\ = (\\sqrt{1} + \\sqrt{2} + \\sqrt{3}) + (\\sqrt{20} + \\sqrt{40} + \\sqrt{60}) = B$ <br\/> V\u1eady A < B <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":3}]}],"id_ques":491},{"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":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/daiso/bai10/lv3/img\/2.jpg' \/><\/center> T\u00ednh $\\sqrt{1 + 2 + ... +(n - 1) + n + (n - 1) + ... + 2 + 1}$ <br\/> (v\u1edbi $n \\in \\mathbb{N^{*}}$) ","select":["A. $n$ ","B. $2n$","C. $n^{2}$","D. $n+ 1$"],"hint":"S\u1eed d\u1ee5ng: $1 + 2 + 3 + ... + (n - 1) + n = \\dfrac{n(n+1)}{2} $","explain":" Ta c\u00f3: $\\sqrt{1 + 2 + ... +(n - 1) + n + (n - 1) + ... + 2 + 1} \\\\ = \\sqrt{2[1 + 2 + 3 + ... + (n - 1)] + n} \\\\ = \\sqrt{2[1 + 2 + 3 + ... + (n - 1) + n] - n} \\\\ = \\sqrt{2.\\dfrac{n(n+1)}{2} - n} \\\\ = \\sqrt{n(n+1) - n} \\\\ = \\sqrt{n^{2}+n-n} \\\\ = \\sqrt{n^{2}} \\\\ = n$ <span class='basic_left'> <b> Nh\u1eadn x\u00e9t <\/b> <br\/> T\u00ednh t\u1ed5ng c\u1ee7a d\u00e3y s\u1ed1 c\u00e1ch \u0111\u1ec1u: <br\/> T\u1ed5ng = $\\dfrac{\\text{[(s\u1ed1 \u0111\u1ea7u + s\u1ed1 cu\u1ed1i).s\u1ed1 l\u01b0\u1ee3ng s\u1ed1 h\u1ea1ng]}}{\\text{2}}$ <\/span> <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":2}]}],"id_ques":492},{"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":" C\u00f3 hay kh\u00f4ng gi\u00e1 tr\u1ecb c\u1ee7a $x$ th\u1ecfa m\u00e3n \u0111i\u1ec1u ki\u1ec7n sau: <br\/> $2016.\\sqrt{(1+x)^{2}} + $ $2017.\\sqrt{(1-x)^{2}} = 0$ ? ","select":["C\u00f3 ","Kh\u00f4ng "],"hint":"S\u1eed s\u1ee5ng $\\sqrt{x} \\geq 0$ v\u1edbi m\u1ecdi gi\u00e1 tr\u1ecb c\u1ee7a $x$. ","explain":" <span class='basic_left'> V\u1edbi m\u1ecdi gi\u00e1 tr\u1ecb c\u1ee7a $x$ ta c\u00f3: <br\/> $2016.\\sqrt{(1+x)^{2}} \\geq 0$ v\u00e0 $2017.\\sqrt{(1-x)^{2}} \\geq 0$ <br\/> Do \u0111\u00f3 $2016.\\sqrt{(1+x)^{2}} + 2017.\\sqrt{(1-x)^{2}} = 0$ <br\/> $\\Leftrightarrow \\begin{cases} 2016.\\sqrt{(1+x)^{2}} = 0 \\\\ 2017.\\sqrt{(1-x)^{2}} = 0 \\end{cases} $ <br\/> $\\Leftrightarrow \\begin{cases} 1 + x = 0 \\\\ 1- x = 0 \\end{cases} $ <br\/> $\\Leftrightarrow \\begin{cases} x = -1 \\\\ x = 1 \\end{cases} $ (v\u00f4 l\u00ed) <br\/> V\u1eady kh\u00f4ng c\u00f3 gi\u00e1 tr\u1ecb n\u00e0o c\u1ee7a $x$ th\u1ecfa m\u00e3n \u0111i\u1ec1u ki\u1ec7n c\u1ee7a \u0111\u1ec1 b\u00e0i. <span class='basic_left'> <b> Nh\u1eadn x\u00e9t: <\/b> <br\/> VT = $2016.\\sqrt{(1+x)^{2}} + 2017.\\sqrt{(1-x)^{2}} > 0$ v\u1edbi m\u1ecdi gi\u00e1 tr\u1ecb c\u1ee7a $x$. <\/span><br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n l\u00e0 Kh\u00f4ng. <\/span><\/span> ","column":2}]}],"id_ques":493},{"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":"T\u00ecm c\u00e1c s\u1ed1 $x, y, z$ th\u1ecfa m\u00e3n \u0111\u1eb3ng th\u1ee9c: <br\/> $\\sqrt{(x-\\sqrt{2})^{2}} + \\sqrt{(y+\\sqrt{2})^{2}} $ $+ |x + y + z| = 0$ ","select":["A. $ x = \\sqrt{2} ; y = - \\sqrt{2} ; z = 0 $ ","B. $ x = 2 ; y = - 2 ; z = 0 $ ","C. $ x = 4 ; y = - 4 ; z = 0 $ ","D. $ x = 1; y = - 1 ; z = 0 $ "],"hint":"C\u00f3: $\\sqrt{a} + \\sqrt{b} + \\sqrt{c} = 0 \\Leftrightarrow \\begin{cases} a = 0 \\\\ b = 0 \\\\ c = 0 \\end{cases}$ ","explain":"<span class='basic_left'> Ta c\u00f3, v\u1edbi m\u1ecdi gi\u00e1 tr\u1ecb c\u1ee7a $x$ th\u00ec $\\sqrt{(x-\\sqrt{2})^{2}} \\geq 0$ <br\/> V\u1edbi m\u1ecdi gi\u00e1 tr\u1ecb c\u1ee7a $y$ th\u00ec $\\sqrt{(y+\\sqrt{2})^{2}} \\geq 0$ <br\/> V\u1edbi m\u1ecdi $x, y, z$ th\u00ec $|x + y + z| \\geq 0$ <br\/> Do \u0111\u00f3 $\\sqrt{(x-\\sqrt{2})^{2}} + \\sqrt{(y+\\sqrt{2})^{2}} $ $+ |x + y + z| = 0$ <br\/> khi v\u00e0 ch\u1ec9 khi c\u1ea3 ba s\u1ed1 h\u1ea1ng \u0111\u1ed3ng th\u1eddi b\u1eb1ng 0, t\u1ee9c l\u00e0: <br\/> $ \\begin{cases} \\sqrt{(x-\\sqrt{2})^{2}} = 0 \\\\ \\sqrt{(y+\\sqrt{2})^{2}} = 0 \\\\ |x + y + z| = 0 \\end{cases}$ <br\/> <br\/> $ \\Leftrightarrow \\begin{cases} x - \\sqrt{2} = 0 \\\\ y + \\sqrt{2} = 0 \\\\ | x + y + z| = 0 \\end{cases}$ <br\/> <\/br\/> $ \\Leftrightarrow \\begin{cases} x = \\sqrt{2} \\\\ y = - \\sqrt{2} \\\\ z = 0 \\end{cases}$ <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span> ","column":2}]}],"id_ques":494},{"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/bai10/lv3/img\/2.jpg' \/><\/center> Cho $a \\in \\mathbb{Q}, b \\in \\mathbb{I}$. <br\/> Khi \u0111\u00f3 $a + b$ l\u00e0: ","select":[" S\u1ed1 h\u1eefu t\u1ec9 "," S\u1ed1 v\u00f4 t\u1ec9 "],"hint":"- Gi\u1ea3 s\u1eed a + b l\u00e0 s\u1ed1 h\u1eefu t\u1ec9. <br\/> - Ki\u1ec3m tra xem \u0111i\u1ec1u gi\u1ea3 s\u1eed c\u00f3 \u0111\u00fang hay kh\u00f4ng. ","explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span> <br\/> * $\\mathbb{Q}$ k\u00ed hi\u1ec7u t\u1eadp h\u1ee3p c\u00e1c s\u1ed1 h\u1eefu t\u1ec9, l\u00e0 s\u1ed1 \u0111\u01b0\u1ee3c vi\u1ebft d\u01b0\u1edbi d\u1ea1ng ph\u00e2n s\u1ed1 $\\dfrac{a}{b}$ v\u1edbi $a,b \u2208 \\mathbb{Z} , b \u2260 0$. <br\/> * $\\mathbb{I}$ k\u00ed hi\u1ec7u t\u1eadp h\u1ee3p c\u00e1c s\u1ed1 v\u00f4 t\u1ec9 l\u00e0 s\u1ed1 vi\u1ebft \u0111\u01b0\u1ee3c d\u01b0\u1edbi d\u1ea1ng s\u1ed1 th\u1eadp ph\u00e2n v\u00f4 h\u1ea1n kh\u00f4ng tu\u1ea7n ho\u00e0n. <\/span> <br\/> <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3: $a \\in \\mathbb{Q}, b \\in \\mathbb{I}$. <br\/> Gi\u1ea3 s\u1eed $a + b = x$ l\u00e0 m\u1ed9t s\u1ed1 h\u1eefu t\u1ec9. <br\/> Khi \u0111\u00f3 $b = x - a$, m\u00e0 $a \\in \\mathbb{Q}, x \\in \\mathbb{Q}$ n\u00ean $b \\in \\mathbb{Q}$, <br\/> \u0111i\u1ec1u n\u00e0y m\u00e2u thu\u1eabn v\u1edbi gi\u1ea3 thi\u1ebft $b \\in \\mathbb{I}$. <br\/> V\u1eady \u0111i\u1ec1u gi\u1ea3 s\u1eed l\u00e0 sai. <br\/> Do \u0111\u00f3 $a + b$ kh\u00f4ng ph\u1ea3i l\u00e0 s\u1ed1 h\u1eefu t\u1ec9. <br\/> <span class='basic_pink'> V\u1eady a + b l\u00e0 s\u1ed1 v\u00f4 t\u1ec9. <\/span><\/span> ","column":2}]}],"id_ques":495},{"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":" T\u00ecm kh\u1eb3ng \u0111\u1ecbnh \u0111\u00fang trong c\u00e1c kh\u1eb3ng \u0111\u1ecbnh sau: ","select":["A. T\u1ed5ng c\u1ee7a hai s\u1ed1 v\u00f4 t\u1ec9 l\u00e0 m\u1ed9t s\u1ed1 v\u00f4 t\u1ec9. ","B. T\u00edch c\u1ee7a hai s\u1ed1 v\u00f4 t\u1ec9 l\u00e0 m\u1ed9t s\u1ed1 v\u00f4 t\u1ec9. ","C. T\u1ed5ng c\u1ee7a m\u1ed9t s\u1ed1 h\u1eefu t\u1ec9 v\u00e0 m\u1ed9t s\u1ed1 v\u00f4 t\u1ec9 l\u00e0 m\u1ed9t s\u1ed1 v\u00f4 t\u1ec9.","D. Th\u01b0\u01a1ng c\u1ee7a hai s\u1ed1 v\u00f4 t\u1ec9 l\u00e0 m\u1ed9t s\u1ed1 v\u00f4 t\u1ec9."],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span> <br\/> * $\\mathbb{Q}$ k\u00ed hi\u1ec7u t\u1eadp h\u1ee3p c\u00e1c s\u1ed1 h\u1eefu t\u1ec9, l\u00e0 s\u1ed1 \u0111\u01b0\u1ee3c vi\u1ebft d\u01b0\u1edbi d\u1ea1ng ph\u00e2n s\u1ed1 $\\dfrac{a}{b}$ v\u1edbi $a,b \u2208 \\mathbb{Z} , b \u2260 0$. <br\/> * $\\mathbb{I}$ k\u00ed hi\u1ec7u t\u1eadp h\u1ee3p c\u00e1c s\u1ed1 v\u00f4 t\u1ec9 l\u00e0 s\u1ed1 vi\u1ebft \u0111\u01b0\u1ee3c d\u01b0\u1edbi d\u1ea1ng s\u1ed1 th\u1eadp ph\u00e2n v\u00f4 h\u1ea1n kh\u00f4ng tu\u1ea7n ho\u00e0n. <\/span> <br\/> <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <br\/> A. Sai. VD: $\\sqrt{3}$ v\u00e0 $-\\sqrt{3}$ l\u00e0 hai s\u1ed1 v\u00f4 t\u1ec9, nh\u01b0ng $\\sqrt{3} + (-\\sqrt{3}) = 0$ l\u00e0 s\u1ed1 h\u1eefu t\u1ec9. <br\/> B. Sai. VD: $3\\sqrt{5}$ v\u00e0 $-\\sqrt{5}$ l\u00e0 hai s\u1ed1 v\u00f4 t\u1ec9, nh\u01b0ng $3\\sqrt{5} . (-\\sqrt{5}) = -15$ l\u00e0 s\u1ed1 h\u1eefu t\u1ec9. <br\/> D. Sai. VD: $7\\sqrt{6}$ v\u00e0 $2\\sqrt{6}$ l\u00e0 hai s\u1ed1 v\u00f4 t\u1ec9, nh\u01b0ng $7\\sqrt{6} : 2\\sqrt{6} = \\dfrac{7}{2}$ l\u00e0 s\u1ed1 h\u1eefu t\u1ec9. <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":1}]}],"id_ques":496},{"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":" R\u00fat g\u1ecdn bi\u1ec3u th\u1ee9c sau theo c\u00e1ch h\u1ee3p l\u00ed: <br\/> $A = \\dfrac{1-\\dfrac{1}{\\sqrt{49}}+\\dfrac{1}{49}-\\dfrac{1}{(7\\sqrt{7})^{2}}}{\\dfrac{\\sqrt{64}}{2}-\\dfrac{4}{7}+\\left(\\dfrac{2}{7}\\right)^{2}-\\dfrac{4}{343}} $ ","select":["A. $\\dfrac{1}{8}$ ","B. $\\dfrac{1}{16}$ ","C. $\\dfrac{1}{4}$","D. $\\dfrac{1}{2}$"],"hint":"Bi\u1ebfn \u0111\u1ed5i m\u1eabu th\u1ee9c r\u1ed3i r\u00fat g\u1ecdn v\u1edbi t\u1eed.","explain":" Ta c\u00f3: $A = \\dfrac{1-\\dfrac{1}{\\sqrt{49}}+\\dfrac{1}{49}-\\dfrac{1}{(7\\sqrt{7})^{2}}}{\\dfrac{\\sqrt{64}}{2}-\\dfrac{4}{7}+\\left(\\dfrac{2}{7}\\right)^{2}-\\dfrac{4}{343}} \\\\ = \\dfrac{1-\\dfrac{1}{7}+\\dfrac{1}{49}-\\dfrac{1}{343}}{\\dfrac{8}{2}-\\dfrac{4}{7}+\\dfrac{4}{49}-\\dfrac{4}{343}} \\\\ = \\dfrac{1-\\dfrac{1}{7}+\\dfrac{1}{49}-\\dfrac{1}{343}}{4\\left(1-\\dfrac{1}{7}+\\dfrac{1}{49}-\\dfrac{1}{343}\\right)} \\\\ = \\dfrac{1}{4}$ <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 C. <\/span><\/span> ","column":4}]}],"id_ques":497},{"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\u00ednh theo c\u00e1ch h\u1ee3p l\u00ed gi\u00e1 tr\u1ecb bi\u1ec3u th\u1ee9c sau: <br\/> $M = 1 - \\dfrac{5}{\\sqrt{196}} - \\dfrac{5}{(2\\sqrt{21})^{2}} - $ $ \\dfrac{\\sqrt{25}}{204} - \\dfrac{(\\sqrt{5})^{2}}{374} $ ","select":["A. $\\dfrac{1}{2}$ ","B. $\\dfrac{6}{11}$ ","C. $\\dfrac{5}{11}$","D. $\\dfrac{1}{17}$"],"hint":"L\u01b0u \u00fd: $ \\dfrac{5}{14} = \\dfrac{5}{2.7} = \\dfrac{1}{2} - \\dfrac{1}{7} \\\\ \\dfrac{5}{84} = \\dfrac{5}{7.12} = \\dfrac{1}{7} - \\dfrac{1}{12}$","explain":"<span class='basic_left'> Ta c\u00f3: $M = 1 - \\dfrac{5}{\\sqrt{196}} - \\dfrac{5}{(2\\sqrt{21})^{2}} - $ $ \\dfrac{\\sqrt{25}}{204} - \\dfrac{(\\sqrt{5})^{2}}{374} $ <br\/> $ = 1 - \\dfrac{5}{14} - \\dfrac{5}{84} - \\dfrac{5}{204} - \\dfrac{5}{374} $ <br\/> $ = 1 - \\left(\\dfrac{5}{2.7} + \\dfrac{5}{7.12} + \\dfrac{5}{12.17} + \\dfrac{5}{17.22} \\right) $ <br\/> $ = 1 - \\left[\\left(\\dfrac{1}{2} - \\dfrac{1}{7} \\right) + \\left(\\dfrac{1}{7} - \\dfrac{1}{12} \\right) + \\left(\\dfrac{1}{12} - \\dfrac{1}{17} \\right) + \\left(\\dfrac{1}{17} - \\dfrac{1}{22} \\right)\\right] $ <br\/> $ = 1 - \\left(\\dfrac{1}{2} - \\dfrac{1}{22} \\right) $ <br\/> $ = 1 - \\dfrac{10}{22} $ <br\/> $ = \\dfrac{6}{11}$ <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":4}]}],"id_ques":498},{"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":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop7/toan/daiso/bai10/lv3/img\/4.jpg'\/><\/center> Kh\u1eb3ng \u0111\u1ecbnh \u0111\u00fang trong c\u00e1c c\u00e1ch vi\u1ebft sau l\u00e0: ","select":["A. $\\mathbb{Q} \\subset \\mathbb{Z}$ ","B. $\\mathbb{I} \\subset \\mathbb{Q}$ ","C. $\\mathbb{R} \\subset \\mathbb{Q}$ ","D. $\\mathbb{I} \\subset \\mathbb{R}$ "],"explain":" <span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span> <br\/> Ta c\u00f3: $\\mathbb{Q}$ l\u00e0 t\u1eadp h\u1ee3p c\u00e1c s\u1ed1 h\u1eefu t\u1ec9, l\u00e0 s\u1ed1 \u0111\u01b0\u1ee3c vi\u1ebft d\u01b0\u1edbi d\u1ea1ng ph\u00e2n s\u1ed1 $\\dfrac{a}{b}$ v\u1edbi $a,b \u2208 \\mathbb{Z} , b \u2260 0$. <br\/> $\\mathbb{Z}$ l\u00e0 t\u1eadp h\u1ee3p c\u00e1c s\u1ed1 nguy\u00ean, bao g\u1ed3m $\u2026,-2 ;-1 ;0 ;1 ;2 ;\u2026$ <br\/> $\\mathbb{I}$ t\u1eadp h\u1ee3p c\u00e1c s\u1ed1 v\u00f4 t\u1ec9 l\u00e0 s\u1ed1 vi\u1ebft \u0111\u01b0\u1ee3c d\u01b0\u1edbi d\u1ea1ng s\u1ed1 th\u1eadp ph\u00e2n v\u00f4 h\u1ea1n kh\u00f4ng tu\u1ea7n ho\u00e0n. <br\/> $\\mathbb{R}$ t\u1eadp h\u1ee3p c\u00e1c s\u1ed1 th\u1ef1c bao g\u1ed3m c\u00e1c s\u1ed1 h\u1eefu t\u1ec9 v\u00e0 c\u00e1c s\u1ed1 v\u00f4 t\u1ec9. <\/span> <br\/> <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> T\u1eadp h\u1ee3p c\u00e1c s\u1ed1 v\u00f4 t\u1ec9 $\\mathbb{I}$ l\u00e0 t\u1eadp h\u1ee3p con c\u1ee7a t\u1eadp h\u1ee3p c\u00e1c s\u1ed1 th\u1ef1c $\\mathbb{R}$ <br\/> n\u00ean $\\mathbb{I} \\subset \\mathbb{R}$ <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 D. <\/span><\/span> ","column":2}]}],"id_ques":499},{"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":" Bi\u1ebft $x + 3\\sqrt{5} = y + 2\\sqrt{9}$ v\u00e0 $ y + 6 < z + 6$ <br\/> S\u1eafp x\u1ebfp c\u00e1c s\u1ed1 theo th\u1ee9 t\u1ef1 t\u0103ng d\u1ea7n l\u00e0: ","select":["A. $z, y, x$","B. $x, y, z$","C. $y, x, z$","D. $z, x, y$"],"hint":"C\u00f3: $2\\sqrt{9} = 2.3 = 6 $","explain":" Ta c\u00f3: $x + 3\\sqrt{5} = y + 2\\sqrt{9} \\\\ \\Leftrightarrow x + 3\\sqrt{5} = y + 6 $ <br\/> Ta th\u1ea5y $3\\sqrt{5} > 6 (6,7 > 6)$ <br\/> Suy ra $y > x$ <br\/> M\u1eb7t kh\u00e1c $y + 6 < z + 6 \\\\ \\Leftrightarrow y < z$ <br\/> Do \u0111\u00f3 $x < y < z$ <br\/> V\u1eady s\u1eafp x\u1ebfp c\u00e1c s\u1ed1 \u0111\u00e3 cho theo th\u1ee9 t\u1ef1 t\u0103ng d\u1ea7n l\u00e0 $x, y, z.$ <br\/> <br\/> <span class='basic_pink'> \u0110\u00e1p \u00e1n \u0111\u00fang l\u00e0 B. <\/span><\/span> ","column":2}]}],"id_ques":500}],"lesson":{"save":0,"level":3}}