{"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":5,"ques":"V\u1edbi $x \\ge 1$. Gi\u1ea3i b\u1ea5t ph\u01b0\u01a1ng tr\u00ecnh sau:<br\/> $\\sqrt{x-1}>3$ ","select":["A. $x >2$","B. $1\\le x < 10$","C. $1\\le x < 2$ ","D. $x >10$ "],"hint":"B\u00ecnh ph\u01b0\u01a1ng hai v\u1ebf","explain":"<span class='basic_left'>V\u1edbi $x \\ge 1$. Ta c\u00f3:<br\/>$\\sqrt{x-1}>3 \\\\ \\Leftrightarrow x-1>9 \\\\ \\Leftrightarrow x > 10$ <br\/>K\u1ebft h\u1ee3p v\u1edbi \u0111i\u1ec1u ki\u1ec7n, ta c\u00f3 $x>10$.<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D <\/span><\/span>","column":2}]}],"id_ques":461},{"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":"V\u1edbi $x \\ge -2$. Gi\u1ea3i b\u1ea5t ph\u01b0\u01a1ng tr\u00ecnh sau:<br\/> $\\sqrt{x+2}>2$ ","select":["A. $x >2$","B. $x >6$ ","C. $-2\\le x < 2$ ","D. $x <4$ "],"hint":"B\u00ecnh ph\u01b0\u01a1ng hai v\u1ebf","explain":"<span class='basic_left'>V\u1edbi $x \\ge -2$. Ta c\u00f3:<br\/>$\\sqrt{x+2}>2 \\\\ \\Leftrightarrow x+2>4 \\\\ \\Leftrightarrow x > 2$ <br\/>K\u1ebft h\u1ee3p v\u1edbi \u0111i\u1ec1u ki\u1ec7n, ta c\u00f3 $x>2$.<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A. <\/span><\/span>","column":2}]}],"id_ques":462},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["2"],["x"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","type_check":"","ques":" V\u1edbi $x<2$, ta c\u00f3 $\\sqrt{4-4x+x^2}=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}-\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}$","hint":"V\u1edbi m\u1ecdi s\u1ed1 $a$, ta c\u00f3 $\\sqrt{a^2}=|a|$","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\sqrt{4-4x+x^2}= \\sqrt{(2-x)^2}=|2-x|=2-x$ (v\u00ec $2-x \\ge 0$ v\u1edbi m\u1ecdi $x<2$)<br\/><span class='basic_pink'>V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $2$ v\u00e0 $x$<\/span><\/span>"}]}],"id_ques":463},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["2"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","type_check":"","ques":" R\u00fat g\u1ecdn $A=\\sqrt{3+2\\sqrt{2}}+\\sqrt{3-2\\sqrt{2}}$<br\/>\u0110\u00e1p s\u1ed1 $A=2\\sqrt{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}}$","hint":"\u0110\u01b0a bi\u1ec3u th\u1ee9c trong c\u0103n v\u1ec1 b\u00ecnh ph\u01b0\u01a1ng m\u1ed9t t\u1ed5ng ho\u1eb7c m\u1ed9t hi\u1ec7u r\u1ed3i \u00e1p d\u1ee5ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c $\\sqrt{a^2}=|a|$ \u0111\u1ec3 r\u00fat g\u1ecdn","explain":"<span class='basic_left'>$\\sqrt{3+2\\sqrt{2}}=\\sqrt{2+2.\\sqrt{2}.1+1}=\\sqrt{(\\sqrt{2}+1)^2}=|\\sqrt{2}+1|=\\sqrt{2}+1$<br\/>$\\sqrt{3-2\\sqrt{2}}=\\sqrt{2-2.\\sqrt{2}.1+1}=\\sqrt{(\\sqrt{2}-1)^2}=|\\sqrt{2}-1|=\\sqrt{2}-1$ (v\u00ec $\\sqrt{2}>1$)<br\/>Suy ra $A=\\sqrt{2}+1+\\sqrt{2}-1=2\\sqrt{2}$<br\/><span class='basic_pink'>V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $2$ <\/span><\/span>"}]}],"id_ques":464},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["2a"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","type_check":"","ques":" V\u1edbi $a\\ge 0$. R\u00fat g\u1ecdn bi\u1ec3u th\u1ee9c:<br\/> $\\sqrt{25a^2}-3a=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}$","hint":"V\u1edbi m\u1ecdi s\u1ed1 $a$, ta c\u00f3 $\\sqrt{a^2}=|a|$","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\sqrt{25a^2}-3a=\\sqrt{{{(5a)}^{2}}}-3a=|5a|- 3a=5a-3a=2a$ (do $a\\ge 0$ n\u00ean $|5a|=5a$) <br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $2a$<\/span><\/span>"}]}],"id_ques":465},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["-a"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","type_check":"","ques":" V\u1edbi $a< 0$. R\u00fat g\u1ecdn bi\u1ec3u th\u1ee9c:<br\/>$\\sqrt{16a^2}+3a=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}$","hint":"V\u1edbi m\u1ecdi s\u1ed1 $a$, ta c\u00f3 $\\sqrt{a^2}=|a|$","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\sqrt{16a^2}+3a=\\sqrt{{{(4a)}^{2}}}+3a=|4a|+3a=-4a+3a=-a$ (do $a < 0$ n\u00ean $|4a|=-4a$)<br\/><span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n \u0111\u00e1p \u00e1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $-a$<\/span><\/span> "}]}],"id_ques":466},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["6","-6"],["-6","6"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","type_check":"","ques":"T\u00ecm $x$ bi\u1ebft: $\\sqrt{9x^2}=|-18|$ <br\/>\u0110\u00e1p s\u1ed1:$\\left[ \\begin{array}{} x = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\\\ x = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\end{array} \\right.$","hint":"V\u1edbi m\u1ecdi s\u1ed1 $a$, ta c\u00f3 $\\sqrt{a^2}=|a|$","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\sqrt{9x^2}=|-18|$<br\/>$\\,\\Leftrightarrow\\sqrt{{{(3x)}^{2}}}=18$<br\/>$\\,\\Leftrightarrow \\left| 3x \\right|=18$<br\/>$\\,\\Leftrightarrow \\left[ \\begin{aligned}& 3x=18 \\\\ & 3x=-18 \\\\ \\end{aligned} \\right.$<br\/>$\\Leftrightarrow \\left[ \\begin{aligned} & x=6 \\\\ & x=-6 \\\\ \\end{aligned} \\right.$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\{6; -6\\}$<\/span> <br\/><span class='basic_left'><span class='basic_pink'>Do \u0111\u00f3 c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $6$ v\u00e0 $-6.$<\/span> <\/span>"}]}],"id_ques":467},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["15","-15"],["-15","15"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","type_check":"","ques":"T\u00ecm $x$ bi\u1ebft: $\\sqrt{x^2}=15$ <br\/>\u0110\u00e1p s\u1ed1:$\\left[ \\begin{array}{} x = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\\\ x = \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\end{array} \\right.$","hint":"V\u1edbi m\u1ecdi s\u1ed1 $a$, ta c\u00f3 $\\sqrt{a^2}=|a|$","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\sqrt{{{x}^{2}}}=15\\Leftrightarrow \\left| x \\right|=15\\Leftrightarrow x=\\pm 15$ <br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\{15; -15\\}$<\/span> <br\/><span class='basic_left'><span class='basic_pink'>Do \u0111\u00f3 c\u00e1c s\u1ed1 c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $15$ v\u00e0 $-15.$<\/span> <\/span>"}]}],"id_ques":468},{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"$\\sqrt{a^2+1}$ x\u00e1c \u0111\u1ecbnh v\u1edbi m\u1ecdi $a >-1$ ","select":["A. \u0110\u00fang","B. Sai"],"hint":"\u0110i\u1ec1u ki\u1ec7n x\u00e1c \u0111\u1ecbnh c\u1ee7a $\\sqrt{A}$ l\u00e0 $A \\ge 0$","explain":"<span class='basic_left'>Ta c\u00f3:<br\/> $a^2+1 > 0$ v\u1edbi m\u1ecdi $a$<br\/>Suy ra $\\sqrt{a^2+1}$ x\u00e1c \u0111\u1ecbnh v\u1edbi m\u1ecdi $a$<br\/><span class='basic_pink'>Do \u0111\u00f3 kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 Sai <\/span>","column":2}]}],"id_ques":469},{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"$\\sqrt{4{{\\text{a}}^{2}}+4\\text{a}+1}$ x\u00e1c \u0111\u1ecbnh v\u1edbi m\u1ecdi $a$ ","select":["A. \u0110\u00fang","B. Sai"],"hint":"S\u1eed d\u1ee5ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c bi\u1ebfn \u0111\u1ed5i bi\u1ec3u th\u1ee9c d\u01b0\u1edbi d\u1ea5u c\u0103n.","explain":"<span class='basic_left'>Ta c\u00f3:<br\/> $\\sqrt{4{a^2}+4a+1}=\\sqrt{{(2a+1)}^2}$<br\/>Ta c\u00f3: ${(2a+1)}^2\\ge 0$ $\\forall a$<br\/>Do \u0111\u00f3, $\\sqrt{4a^2+4a+1}$ x\u00e1c \u0111\u1ecbnh v\u1edbi m\u1ecdi $a$. <br\/> <span class='basic_pink'> V\u1eady kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 \u0110\u00fang <\/span>","column":2}]}],"id_ques":470},{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"$\\sqrt{{{\\left( a+3 \\right)}^{2}}}=-(a+3)$ v\u1edbi m\u1ecdi $a\\le -3$ ","select":["A. \u0110\u00fang","B. Sai"],"hint":"V\u1edbi m\u1ecdi s\u1ed1 $a$, ta c\u00f3 $\\sqrt{a^2}=|a|$ ","explain":"<span class='basic_left'>Ta c\u00f3: $a\\le -3 \\Leftrightarrow a + 3 \\le 0 $ <br\/>Suy ra, $\\sqrt{{{\\left( a+3 \\right)}^{2}}}=|a+3|=-(a+3)$ <br\/><span class='basic_pink'> V\u1eady kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 \u0110\u00fang <\/span><\/span>","column":2}]}],"id_ques":471},{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/daiso/bai2/lv1/img\/1.png' \/><\/center> $a-9=\\left( \\sqrt{a}-3 \\right)\\left( \\sqrt{a}+3 \\right)$ v\u1edbi m\u1ecdi $a \\ge 0$ ","select":["A. \u0110\u00fang","B. Sai"],"hint":"","explain":"<span class='basic_left'>V\u1edbi $a \\ge 0$, ta c\u00f3: <br\/>$a - 9 = (\\sqrt{a})^2 - 3^2 = (\\sqrt{a} - 3) (\\sqrt{a} + 3)$<br\/><span class='basic_pink'> V\u1eady kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 \u0110\u00fang<\/span><\/span>","column":2}]}],"id_ques":472},{"time":24,"part":[{"title":"\u0110i\u1ec1n \u0111\u00e1p \u00e1n v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["x"],["5"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","ques":" V\u1edbi $x \\ge 0,$ ho\u00e0n thi\u1ec7n v\u1ebf tr\u00e1i trong \u0111\u1eb3ng th\u1ee9c sau:<br\/>_input_$- 2\\sqrt{5x}+$_input_$=\\left( \\sqrt{x}-\\sqrt{5} \\right)^2$","hint":"S\u1eed d\u1ee5ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c b\u00ecnh ph\u01b0\u01a1ng c\u1ee7a m\u1ed9t hi\u1ec7u \u0111\u1ec3 khai tri\u1ec3n v\u1ebf ph\u1ea3i t\u1eeb \u0111\u00f3 suy ra h\u1ea1ng t\u1eed c\u1ea7n t\u00ecm \u1edf v\u1ebf tr\u00e1i.","explain":"<span class='basic_left'>V\u1edbi $x \\ge 0,$ ta c\u00f3:<br\/>${{\\left( \\sqrt{x}-\\sqrt{5} \\right)}^{2}}$<br\/>$\\,=(\\sqrt{x})^2-2.\\sqrt{x}.\\sqrt{5}+(\\sqrt{5})^2$<br\/>$\\,=x-2\\sqrt{5x}+5$<br\/><span class='basic_pink'>V\u1eady hai \u00f4 tr\u1ed1ng c\u1ea7n \u0111i\u1ec1n l\u00e0 $x$ v\u00e0 $5$ <\/span><\/span>"}]}],"id_ques":473},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["x"],["11"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","ques":"$x^2-11=(\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}-\\sqrt{11})(x+\\sqrt{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}})$","hint":"S\u1eed d\u1ee5ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c $a^2-b^2=(a-b)(a+b)$ ","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>${{x}^{2}}-11=x^2-\\sqrt{{{11}^{2}}}$$\\,=\\left( x-\\sqrt{11} \\right)\\left( x+\\sqrt{11} \\right)$<br\/><span class='basic_pink'>V\u1eady hai \u00f4 tr\u1ed1ng c\u1ea7n \u0111i\u1ec1n l\u00e0 $x$ v\u00e0 $11$ <\/span><\/span>"}]}],"id_ques":474},{"time":24,"part":[{"title":"\u0110i\u1ec1n d\u1ea5u $> , <, =$ th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng:","title_trans":"","temp":"fill_the_blank","correct":[[["<"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","ques":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/daiso/bai2/lv1/img\/2.jpg' \/><\/center>\u0110i\u1ec1u ki\u1ec7n x\u00e1c \u0111\u1ecbnh c\u1ee7a bi\u1ec3u th\u1ee9c $\\sqrt{\\dfrac{-5}{x-2}}$ l\u00e0 $x$ _input_$2$ ","hint":"","explain":"<span class='basic_left'>Bi\u1ec3u th\u1ee9c $\\sqrt{\\dfrac{-5}{x-1}}$ x\u00e1c \u0111\u1ecbnh khi: <br\/>$\\dfrac{-5}{x-2}\\ge 0 \\Leftrightarrow x-2<0 \\Leftrightarrow x<2$ <br\/><span class='basic_pink'>V\u1eady d\u1ea5u c\u1ea7n \u0111i\u1ec1n l\u00e0 $<$ <\/span><\/span>"}]}],"id_ques":475},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank","correct":[[["-4"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","ques":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/daiso/bai2/lv1/img\/1.png' \/><\/center>Gi\u00e1 tr\u1ecb nh\u1ecf nh\u1ea5t c\u1ee7a $x$ \u0111\u1ec3 bi\u1ec3u th\u1ee9c $\\sqrt{x+4}$ x\u00e1c \u0111\u1ecbnh l\u00e0 $x =$_input_ ","hint":"\u0110i\u1ec1u ki\u1ec7n x\u00e1c \u0111\u1ecbnh c\u1ee7a $\\sqrt{A}$ l\u00e0 $A\\ge0$ ","explain":"<span class='basic_left'>Bi\u1ec3u th\u1ee9c $\\sqrt{x+4}$ x\u00e1c \u0111\u1ecbnh khi: <br\/>$x + 4\\ge 0\\Leftrightarrow x \\ge-4$ <br\/>V\u1eady gi\u00e1 tr\u1ecb nh\u1ecf nh\u1ea5t c\u1ee7a $x$ \u0111\u1ec3 bi\u1ec3u th\u1ee9c x\u00e1c \u0111\u1ecbnh l\u00e0 $x =-4$ <br\/><span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $-4$ <\/span><\/span>"}]}],"id_ques":476},{"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":"Gi\u00e1 tr\u1ecb c\u1ee7a $x$ \u0111\u1ec3 $\\sqrt{{{x}^{2}}}=11$ l\u00e0: ","select":["A. $x= 11$ ","B. $x= -11$ ","C. $x= 121$ ","D. $x= \\pm11$ "],"hint":"V\u1edbi m\u1ecdi s\u1ed1 $a$, ta c\u00f3 $\\sqrt{a^2}=|a|$ ","explain":"<span class='basic_left'>Ta c\u00f3: <br\/>$\\sqrt{{{x}^{2}}}=11\\Leftrightarrow |x|=11\\Leftrightarrow x=\\pm11$ .<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 D<\/span>","column":2}]}],"id_ques":477},{"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":"K\u1ebft qu\u1ea3 c\u1ee7a ph\u00e9p t\u00ednh $\\sqrt{{{\\left( \\dfrac{1}{\\sqrt{2}}-\\dfrac{1}{\\sqrt{3}} \\right)}^{2}}}$ l\u00e0: ","select":["A. $\\dfrac{1}{\\sqrt{2}}-\\dfrac{1}{\\sqrt{3}}$ ","B. $\\dfrac{1}{\\sqrt{2}}+\\dfrac{1}{\\sqrt{3}}$ ","C. $\\dfrac{1}{\\sqrt{3}}-\\dfrac{1}{\\sqrt{2}}$ ","D. $-\\dfrac{1}{\\sqrt{2}}-\\dfrac{1}{\\sqrt{3}}$ "],"hint":"V\u1edbi m\u1ecdi s\u1ed1 $a$, ta c\u00f3 $\\sqrt{a^2}=|a|$ ","explain":"<span class='basic_left'>Ta c\u00f3: $\\sqrt{{{\\left( \\dfrac{1}{\\sqrt{2}}-\\dfrac{1}{\\sqrt{3}} \\right)}^{2}}}$<br\/>$\\,=\\left| \\dfrac{1}{\\sqrt{2}}-\\dfrac{1}{\\sqrt{3}} \\right|$<br\/>$\\,=\\dfrac{1}{\\sqrt{2}}-\\dfrac{1}{\\sqrt{3}}$ (v\u00ec $\\dfrac{1}{\\sqrt{2}}>\\dfrac{1}{\\sqrt{3}}$).<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A<\/span><\/span>","column":2}]}],"id_ques":478},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["1"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","ques":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/daiso/bai2/lv1/img\/1.png' \/><\/center>$5.\\sqrt{{{\\left( -\\dfrac{1}{5} \\right)}^{2}}}=$_input_ ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> V\u1edbi m\u1ecdi s\u1ed1 $a$, ta c\u00f3 $\\sqrt{a^2}=|a|$ <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3:<br\/>$5.\\sqrt{{{\\left( -\\dfrac{1}{5} \\right)}^{2}}}=5.\\left| -\\dfrac{1}{5} \\right|=5.\\dfrac{1}{5}=1$<br\/><span class='basic_pink'>V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $1$<\/span><\/span>"}]}],"id_ques":479},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o \u00f4 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["-8"],["15"]]],"list":[{"point":5,"width":40,"content":"","type_input":"","ques":" <center><img src='https://www.luyenthi123.com/file/luyenthi123/lop9/toan/daiso/bai2/lv1/img\/1.png' \/><\/center>$-\\dfrac{4}{3}\\sqrt{(-0,4)^2}=\\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":"V\u1edbi m\u1ecdi s\u1ed1 $a$, ta c\u00f3 $\\sqrt{a^2}=|a|$ ","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$-\\dfrac{4}{3}\\sqrt{(-0,4)^2}=-\\dfrac{4}{3}.|-0,4|$$\\,=-\\dfrac{4}{3}.0,4=-\\dfrac{4}{3}.\\dfrac{2}{5}=-\\dfrac{8}{15}$<br\/><span class='basic_pink'>V\u1eady s\u1ed1 c\u1ea7n \u0111i\u1ec1n l\u00e0 $-\\dfrac{8}{15}$<\/span><\/span>"}]}],"id_ques":480}],"lesson":{"save":0,"level":1}}