{"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":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai19/lv1/img\/1.jpg' \/><\/center>Ph\u01b0\u01a1ng tr\u00ecnh t\u00edch l\u00e0 ph\u01b0\u01a1ng tr\u00ecnh c\u00f3 d\u1ea1ng:<br\/>(trong \u0111\u00f3 $A(x)$ v\u00e0 $B(x)$ l\u00e0 c\u00e1c \u0111a th\u1ee9c bi\u1ebfn $x$)","select":["A. $A(x).B(x)=0$","B. $A(x).B(x)=C(x)$","C. $A(x)+B(x)=0$","D. $\\dfrac{A(x)}{B(x)}=0$"],"hint":"","explain":"<span class='basic_left'>Ph\u01b0\u01a1ng tr\u00ecnh t\u00edch l\u00e0 ph\u01b0\u01a1ng tr\u00ecnh c\u00f3 d\u1ea1ng $A(x).B(x)=0$, trong \u0111\u00f3 $A(x)$ v\u00e0 $B(x)$ l\u00e0 c\u00e1c \u0111a th\u1ee9c bi\u1ebfn $x$<br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span> ","column":1}]}],"id_ques":841},{"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":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai19/lv1/img\/2.jpg' \/><\/center>Trong hai kh\u1eb3ng \u0111\u1ecbnh sau, kh\u1eb3ng \u0111\u1ecbnh n\u00e0o \u0111\u00fang?","select":["A. $A(x).B(x)=0\\Leftrightarrow A(x)=0\\,\\,\\,\\,\\text{ho\u1eb7c}\\,\\,\\,\\,\\,\\,B(x)=0$","B. $A(x).B(x)=0\\Leftrightarrow A(x)=0\\,\\,\\,\\,\\text{v\u00e0}\\,\\,\\,\\,\\,\\,B(x)=0$"],"hint":"","explain":"<span class='basic_left'>Mu\u1ed1n gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh $A(x)B(x)=0$, ta gi\u1ea3i hai ph\u01b0\u01a1ng tr\u00ecnh $A(x)=0$ v\u00e0 $B(x)=0$ r\u1ed3i l\u1ea5y t\u1ea5t c\u1ea3 c\u00e1c nghi\u1ec7m c\u1ee7a ch\u00fang. T\u1ee9c l\u00e0:<br\/> $A(x).B(x)=0\\Leftrightarrow A(x)=0\\,\\,\\,\\,\\text{ho\u1eb7c}\\,\\,\\,\\,\\,\\,B(x)=0$<br\/>Hay <br\/>$A(x).B(x)=0\\Leftrightarrow \\left[ \\begin{align} & A(x)=0 \\\\ & B(x)=0 \\\\ \\end{align} \\right.$ <br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span>","column":1}]}],"id_ques":842},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["0"],["1"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh $x(x-1)=0.$<br\/> T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{};\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\}$ ","hint":"","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned} & x(x-1)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=0 \\\\ & x-1=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=0 \\\\ & x=1 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady ph\u01b0\u01a1ng tr\u00ecnh c\u00f3 t\u1eadp nghi\u1ec7m $S=\\{0;1\\}$<br\/><span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $0$ v\u00e0 $1$<\/span><\/span>"}]}],"id_ques":843},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["-1"],["-2"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh $(x+1)(x+2)=0.$<br\/> T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{};\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\}$ ","hint":"","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned} & (x+1)(x+2)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x+1=0 \\\\ & x+2=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=-1 \\\\ & x=-2 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <br\/>V\u1eady ph\u01b0\u01a1ng tr\u00ecnh c\u00f3 t\u1eadp nghi\u1ec7m $S=\\{-2;-1\\}$<br\/><span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $-1$ v\u00e0 $-2$<\/span><\/span>"}]}],"id_ques":844},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["0"],["1"],["2"]]],"list":[{"point":5,"width":50,"type_input":"","input_hint":"","ques":"Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh $-x(x-2)(3x-3)=0.$<br\/> T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{};\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{};\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\}$ ","hint":"","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned} & -x(x-2)(3x-3)=0 \\\\ &\\Leftrightarrow \\left[\\begin{aligned}& x=0\\\\ & x-2=0 \\\\ & 3x-3=0 \\\\ \\end{aligned} \\right. \\\\ &\\Leftrightarrow \\left[ \\begin{aligned} & x=0 \\\\ & x=2 \\\\ & x=1 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <br\/>V\u1eady ph\u01b0\u01a1ng tr\u00ecnh c\u00f3 t\u1eadp nghi\u1ec7m $S=\\{0;1;2\\}$<br\/><span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $0$, $1$ v\u00e0 $2$<\/span><\/span>"}]}],"id_ques":845},{"time":24,"part":[{"time":3,"title":"N\u1ed1i m\u1ed7i ph\u01b0\u01a1ng tr\u00ecnh c\u1ed9t tr\u00e1i v\u1edbi s\u1ed1 nghi\u1ec7m t\u01b0\u01a1ng \u1ee9ng \u1edf c\u1ed9t ph\u1ea3i. ","title_trans":"","audio":"","temp":"matching","correct":[["3","2","4","1"]],"list":[{"point":5,"image":"","left":["$x(x-1)(x+1)=0$ ","$2x-{{x}^{2}}=0$","$({{x}^{2}}+4)({{x}^{2}}+1)=0$ ","$x({{x}^{2}}+1)=0$"],"right":["$1$ nghi\u1ec7m","$2$ nghi\u1ec7m","$3$ nghi\u1ec7m","v\u00f4 nghi\u1ec7m"],"top":100,"hint":"","explain":"<span class='basic_left'>+) <br\/>$\\begin{aligned} & x(x-1)(x+1)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=0 \\\\ & x-1=0 \\\\ & x+1=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} &x=0 \\\\ & x=1 \\\\ & x=-1 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <br\/>V\u1eady ph\u01b0\u01a1ng tr\u00ecnh c\u00f3 $3$ nghi\u1ec7m.<br\/>+)<br\/> $\\begin{aligned} & 2x-{{x}^{2}}=0 \\\\ & \\Leftrightarrow x\\left( 2-x \\right)=0 \\\\&\\Leftrightarrow \\left[ \\begin{aligned} & x=0 \\\\ & 2-x=0 \\\\\\end{aligned}\\right.\\\\ &\\Leftrightarrow \\left[ \\begin{aligned} & x=0 \\\\ & x=2 \\\\ \\end{aligned} \\right. \\\\\\end{aligned}$ <br\/>V\u1eady ph\u01b0\u01a1ng tr\u00ecnh c\u00f3 $2$ nghi\u1ec7m.<br\/>+) <br\/>$\\begin{aligned} & \\left( {{x}^{2}}+4 \\right)\\left( {{x}^{2}}+1 \\right)=0 \\\\ &\\Leftrightarrow \\left[ \\begin{aligned} & {{x}^{2}}+4=0 \\\\ & {{x}^{2}}+1=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & {{x}^{2}}=-4\\,\\,\\text{(v\u00f4 nghi\u1ec7m v\u00ec }x^2\\ge 0\\,\\forall\\,x) \\\\ &{{x}^{2}}=-1 \\,\\,\\text{(v\u00f4 nghi\u1ec7m v\u00ec }x^2\\ge 0\\,\\forall\\,x)\\\\ \\end{aligned} \\right. & \\\\ \\end{aligned}$ <br\/>V\u1eady ph\u01b0\u01a1ng tr\u00ecnh v\u00f4 nghi\u1ec7m.<br\/>+) <br\/>$\\begin{aligned} & x\\left( x^2+1 \\right)=0 \\\\ & \\Leftrightarrow \\left[\\begin{aligned} & x=0 \\\\ & x^2+1=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=0 \\\\ & x^2=-1\\,\\,\\text{(v\u00f4 nghi\u1ec7m v\u00ec }x^2\\ge 0\\,\\forall\\,x) \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady ph\u01b0\u01a1ng tr\u00ecnh c\u00f3 1 nghi\u1ec7m.<\/span>"}]}],"id_ques":846},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00fang hay sai","title_trans":"Bi\u1ebfn \u0111\u1ed5i c\u00e1c ph\u01b0\u01a1ng tr\u00ecnh v\u1ec1 d\u1ea1ng ph\u01b0\u01a1ng tr\u00ecnh t\u00edch","temp":"true_false","correct":[["t","t","f","f","t"]],"list":[{"point":5,"image":"","col_name":["","\u0110\u00fang","Sai"],"arr_ques":["$\\begin{aligned} & x(x-1)+2(x-1)=0 \\\\ & \\Leftrightarrow (x+2)(x-1)=0 \\\\ \\end{aligned}$","$x(x-3)+{{x}^{2}}=0\\\\ \\Leftrightarrow x(2x-3)=0$ "," $\\begin{aligned} & {{x}^{2}}-4+2-x=0 \\\\ & \\Leftrightarrow (x-2)(x+3)=0 \\\\ \\end{aligned}$","$\\begin{aligned} & {{x}^{2}}+4x+3=0 \\\\ &\\Leftrightarrow x(x+4)=-3 \\\\ \\end{aligned}$"," $\\begin{aligned} & {{x}^{2}}+1={{x}^{4}}-1 \\\\ & \\Leftrightarrow ({{x}^{2}}+1)(2-{{x}^{2}})=0 \\\\ \\end{aligned}$"],"explain":[" \u0110\u00fang","<br\/> \u0110\u00fang. V\u00ec <br\/>$\\begin{aligned} & x(x-3)+{{x}^{2}}=0 \\\\ & \\Leftrightarrow x(x-3+x)=0 \\\\ &\\Leftrightarrow x(2x-3)=0 \\\\ \\end{aligned}$","<br\/> Sai. V\u00ec <br\/>$\\begin{aligned} & {{x}^{2}}-4+2-x=0 \\\\ & \\Leftrightarrow (x-2)(x+2)-(x-2)=0 \\\\ &\\Leftrightarrow (x-2)(x+2-1)=0 \\\\ & \\Leftrightarrow (x-2)(x+1)=0 \\\\ \\end{aligned}$","<br\/> Sai. V\u00ec<br\/> $\\begin{aligned} & {{x}^{2}}+4x+3=0 \\\\ & \\Leftrightarrow {{x}^{2}}+3x+x+3=0 \\\\ & \\Leftrightarrow x(x+3)+(x+3)=0 \\\\ & \\Leftrightarrow (x+1)(x+3)=0 \\\\ \\end{aligned}$","<br\/>\u0110\u00fang. V\u00ec <br\/>$\\begin{aligned} & {{x}^{2}}+1={{x}^{4}}-1 \\\\ &x^2+1=(x^2-1)(x^2+1)\\\\ &(x^2+1)[1-(x^2-1)]=0\\\\ & \\Leftrightarrow ({{x}^{2}}+1)(2-{{x}^{2}})=0 \\\\ \\end{aligned}$"]}]}],"id_ques":847},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai19/lv1/img\/3.jpg' \/><\/center>Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh $(2x+1)(x-3)=(2x+1)(x+5).$<br\/>T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0:","select":["A. $S=\\varnothing $ ","B. $S=\\{4\\}$","C. $S=\\left\\{ \\dfrac{-1}{2} \\right\\}$ ","D. $S=\\left\\{ \\dfrac{-1}{2};4 \\right\\}$ "],"hint":"Chuy\u1ec3n v\u1ebf v\u00e0 \u0111\u1eb7t nh\u00e2n t\u1eed chung, \u0111\u01b0a ph\u01b0\u01a1ng tr\u00ecnh ban \u0111\u1ea7u v\u1ec1 ph\u01b0\u01a1ng tr\u00ecnh t\u00edch. ","explain":" <span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned}& (2x+1)(x-3)=(2x+1)(x+5) \\\\ & \\Leftrightarrow (2x+1)(x-3)-(2x+1)(x+5)=0 \\\\ & \\Leftrightarrow (2x+1)[ x-3-(x+5)]=0 \\\\ & \\Leftrightarrow (2x+1)(-8)=0 \\\\ & \\Leftrightarrow 2x+1=0 \\\\ & \\Leftrightarrow x=\\dfrac{-1}{2} \\\\ \\end{aligned}$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\left\\{\\dfrac {-1}{2}\\right\\}$ <br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><br\/><b>Sai l\u1ea7m c\u1ea7n tr\u00e1nh:<\/b><br\/>B\u00e0i gi\u1ea3i <span class='basic_green'>sai<\/span>:<br\/>$\\begin{align} & \\left( 2x+1 \\right)\\left( x-3 \\right)=\\left( 2x+1 \\right)\\left( x+5 \\right) \\\\ & \\Leftrightarrow x-3=x+5 \\\\ & \\Leftrightarrow 0.x=8 \\\\ \\end{align}$<br\/>K\u1ebft lu\u1eadn ph\u01b0\u01a1ng tr\u00ecnh v\u00f4 nghi\u1ec7m.<br\/><span class='basic_green'>L\u01b0u \u00fd:<\/span> V\u1edbi nh\u1eefng ph\u01b0\u01a1ng tr\u00ecnh d\u1ea1ng: $A(x).B(x)=A(x)$.<br\/>Ta th\u1ef1c hi\u1ec7n chuy\u1ec3n v\u1ec1 v\u00e0 \u0111\u1eb7t $A(x)$ l\u00e0 nh\u00e2n t\u1eed chung r\u1ed3i \u0111\u01b0a ph\u01b0\u01a1ng tr\u00ecnh ban \u0111\u1ea7u v\u1ec1 d\u1ea1ng ph\u01b0\u01a1ng tr\u00ecnh t\u00edch v\u00e0 gi\u1ea3i. T\u1ee9c l\u00e0:<br\/>$A(x).B(x)=A(x)\\\\ \\Leftrightarrow A(x).[B(x)-1]=0\\\\ \\Leftrightarrow \\left[\\begin{aligned}&A(x)=0\\\\ &B(x)=1\\end{aligned}\\right.$<\/span>","column":2}]}],"id_ques":848},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai19/lv1/img\/3.jpg' \/><\/center>Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh $3x-15=2x\\left( x-5 \\right).$<br\/>T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0:","select":["A. $S=\\left\\{ \\dfrac{3}{2} \\right\\}$ ","B. $S=\\left\\{ \\dfrac{3}{2};5 \\right\\}$ ","C. $S=\\left\\{ \\dfrac{-3}{2};5 \\right\\}$ ","D. $S=\\left\\{ \\dfrac{-3}{2};-5 \\right\\}$ "],"hint":"Chuy\u1ec3n v\u1ebf, \u0111\u1eb7t nh\u00e2n t\u1eed chung \u0111\u01b0a ph\u01b0\u01a1ng tr\u00ecnh \u0111\u00e3 cho v\u1ec1 ph\u01b0\u01a1ng tr\u00ecnh t\u00edch.","explain":" <span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned} & 3x-15=2x(x-5) \\\\ & \\Leftrightarrow 3(x-5)=2x(x-5) \\\\ & \\Leftrightarrow 3(x-5)-2x(x-5)=0 \\\\ & \\Leftrightarrow (x-5)(3-2x)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x-5=0 \\\\ & 3-2x=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=5 \\\\ & 2x=3 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=5 \\\\ & x=\\frac{3}{2} \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\left\\{ \\dfrac{3}{2};5 \\right\\}$<br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span>","column":2}]}],"id_ques":849},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai19/lv1/img\/9.jpg' \/><\/center>Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh ${{x}^{2}}-x=-2x+2.$<br\/>T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0:","select":["A. $S=\\left \\{1\\right\\}$ ","B. $S=\\left\\{ -2\\right\\}$ ","C. $S=\\left\\{ -2;1 \\right\\}$ ","D. $S=\\left\\{ -1;2 \\right\\}$ "],"hint":"Ph\u00e2n t\u00edch v\u1ebf tr\u00e1i v\u00e0 v\u1ebf ph\u1ea3i th\u00e0nh nh\u00e2n t\u1eed r\u1ed3i chuy\u1ec3n v\u1ebf v\u00e0 bi\u1ebfn \u0111\u1ed5i \u0111\u01b0a ph\u01b0\u01a1ng tr\u00ecnh \u0111\u00e3 cho v\u1ec1 d\u1ea1ng ph\u01b0\u01a1ng tr\u00ecnh t\u00edch.","explain":" <span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned} & {{x}^{2}}-x=-2x+2 \\\\ & \\Leftrightarrow x(x-1)=-2(x-1) \\\\ & \\Leftrightarrow x(x-1)+2(x-1)=0 \\\\ & \\Leftrightarrow (x+2)(x-1)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x+2=0\\\\ & x-1=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=-2 \\\\ & x=1 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\left\\{ -2;1 \\right\\}$<br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 C.<\/span><\/span>","column":2}]}],"id_ques":850},{"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":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai19/lv1/img\/16.jpg' \/><\/center>Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh ${{x}^{2}}-6=5x.$<br\/>T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0:","select":["A. $S=\\left \\{-1;6\\right\\}$ ","B. $S=\\left\\{ 0;5\\right\\}$ ","C. $S=\\left\\{ 2;3 \\right\\}$ ","D. $S=\\varnothing$ "],"hint":"Chuy\u1ec3n v\u1ebf, s\u1eed d\u1ee5ng ph\u01b0\u01a1ng ph\u00e1p t\u00e1ch v\u00e0 \u0111\u1eb7t nh\u00e2n t\u1eed chung bi\u1ebfn \u0111\u1ed5i ph\u01b0\u01a1ng tr\u00ecnh \u0111\u00e3 cho v\u1ec1 ph\u01b0\u01a1ng tr\u00ecnh t\u00edch","explain":" <span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned} & {{x}^{2}}-6=5x \\\\ & \\Leftrightarrow {{x}^{2}}-5x-6=0 \\\\ &\\Leftrightarrow {{x}^{2}}-6x+x-6=0 \\\\ & \\Leftrightarrow x(x-6)+(x-6)=0 \\\\ &\\Leftrightarrow (x+1)(x-6)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x+1=0 \\\\ & x-6=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned}& x=-1 \\\\ &x=6 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\left\\{ -1;6 \\right\\}$<br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><\/span>","column":2}]}],"id_ques":851},{"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":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai19/lv1/img\/12.jpg' \/><\/center>Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh: ${{x}^{2}}+4x+4=9$<br\/>T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0:","select":["A. $S=\\left \\{-5;1\\right\\}$ ","B. $S=\\left\\{ -2\\right\\}$ ","C. $S=\\left\\{ -1;5 \\right\\}$ ","D. $S=\\varnothing$ "],"hint":"Chuy\u1ec3n v\u1ebf, s\u1eed d\u1ee5ng ph\u01b0\u01a1ng ph\u00e1p t\u00e1ch v\u00e0 \u0111\u1eb7t nh\u00e2n t\u1eed chung bi\u1ebfn \u0111\u1ed5i ph\u01b0\u01a1ng tr\u00ecnh \u0111\u00e3 cho v\u1ec1 ph\u01b0\u01a1ng tr\u00ecnh t\u00edch","explain":" <span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned} & {{x}^{2}}+4x+4=9 \\\\ & \\Leftrightarrow {{x}^{2}}+4x-5=0 \\\\ &\\Leftrightarrow {{x}^{2}}+5x-x-5=0 \\\\ & \\Leftrightarrow x(x+5)-(x+5)=0 \\\\ &\\Leftrightarrow (x-1)(x+5)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x-1=0 \\\\ & x+5=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=1 \\\\ & x=-5 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\left\\{ 1;-5 \\right\\}$<br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 A.<\/span><br\/><b>Nh\u00e2n x\u00e9t:<\/b> Ngo\u00e0i c\u00e1ch gi\u1ea3i tr\u00ean ta c\u00f3 th\u1ec3 gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh b\u1eb1ng c\u00e1ch sau:<br\/>$\\begin{aligned} & {{x}^{2}}+4x+4=9 \\\\ & \\Leftrightarrow {{\\left( x+2 \\right)}^{2}}={{3}^{2}} \\\\ & \\Leftrightarrow {{\\left( x+2 \\right)}^{2}}-{{3}^{2}}=0 \\\\ & \\Leftrightarrow \\left[ \\left( x+2 \\right)-3 \\right]\\left[ \\left( x+2 \\right)+3 \\right]=0 \\\\ & \\Leftrightarrow \\left( x-1 \\right)\\left( x+5 \\right)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=1 \\\\ & x=-5 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <\/span>","column":2}]}],"id_ques":852},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["0"],["-2"]]],"list":[{"point":5,"width":50,"type_input":"","input_hint":"","ques":"T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh ${{x}^{2}}+2x=0 $ l\u00e0 $S=\\{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{};\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\}$","hint":"\u0110\u1eb7t nh\u00e2n t\u1eed chung \u0111\u01b0a ph\u01b0\u01a1ng tr\u00ecnh \u0111\u00e3 cho v\u1ec1 ph\u01b0\u01a1ng tr\u00ecnh t\u00edch","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned}& {{x}^{2}}+2x=0 \\\\ & \\Leftrightarrow x(x+2)=0 \\\\ & \\Leftrightarrow \\left[\\begin{aligned} & x=0 \\\\ & x+2=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=0 \\\\ & x=-2 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\{-2;0\\}$<br\/><span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o ch\u1ed7 tr\u1ed1ng l\u00e0 $0$ v\u00e0 $-2$<\/span><\/span>"}]}],"id_ques":853},{"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":[[["3"]]],"list":[{"point":5,"width":50,"type_input":"","input_hint":"","ques":"T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh $(x-3)(2x-6)=0$ l\u00e0 $S=\\{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\}$","hint":"","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned} & (x-3)(2x-6)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x-3=0 \\\\ & 2x-6=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=3 \\\\ & 2x=6 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow x=3 \\\\ \\end{aligned}$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\{3\\}$<br\/><span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o ch\u1ed7 tr\u1ed1ng l\u00e0 $3$<\/span><br\/><span class='basic_green'>Nh\u1eadn x\u00e9t:<\/span> Ph\u01b0\u01a1ng tr\u00ecnh tr\u00ean \u0111\u01b0\u1ee3c gi\u1ea3i theo ph\u01b0\u01a1ng tr\u00ecnh t\u00edch d\u1ea1ng $A(x).B(x)=0$.<br\/>Ngo\u00e0i ra, ta c\u00f3 th\u1ec3 th\u1ef1c hi\u1ec7n bi\u1ebfn \u0111\u1ed5i v\u1ebf tr\u00e1i r\u1ed3i gi\u1ea3i nh\u01b0 sau:<br\/>$\\begin{aligned} & (x-3)(2x-6)=0 \\\\ & \\Leftrightarrow (x-3).2.(x-3)=0 \\\\ &\\Leftrightarrow 2{{\\left( x-3 \\right)}^{2}}=0 \\\\ & \\Leftrightarrow x-3=0 \\\\ &\\Leftrightarrow x=3 \\\\ \\end{aligned}$<br\/>V\u1eady ph\u01b0\u01a1ng tr\u00ecnh c\u00f3 t\u1eadp nghi\u1ec7m $S=\\{3\\}$<\/span>"}]}],"id_ques":854},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["-1"],["3"]]],"list":[{"point":5,"width":50,"type_input":"","input_hint":"","ques":"T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh ${{x}^{2}}-2x+1=4$ l\u00e0 $S=\\{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{};\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\}$","hint":"Bi\u1ebfn \u0111\u1ed5i v\u1ec1 tr\u00e1i, \u00e1p d\u1ee5ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c $(a-b)^2$. Chuy\u1ec3n v\u1ebf, \u0111\u01b0a ph\u01b0\u01a1ng tr\u00ecnh \u0111\u00e3 cho v\u1ec1 d\u1ea1ng ph\u01b0\u01a1ng tr\u00ecnh t\u00edch v\u00e0 gi\u1ea3i.","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned} & {{x}^{2}}-2x+1=4 \\\\ & \\Leftrightarrow {{\\left( x-1 \\right)}^{2}}=4 \\\\ & \\Leftrightarrow {{\\left( x-1 \\right)}^{2}}-4=0 \\\\ &\\Leftrightarrow \\left[ \\left( x-1 \\right)+2 \\right].\\left[ \\left( x-1 \\right)-2 \\right]=0 \\\\ &\\Leftrightarrow \\left( x+1 \\right)\\left( x-3 \\right)=0 \\\\ & \\Leftrightarrow \\left[\\begin{aligned} & x+1=0 \\\\ & x-3=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow\\left[ \\begin{aligned} & x=-1 \\\\ & x=3 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\{-1;3\\}$<br\/><span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o ch\u1ed7 tr\u1ed1ng l\u00e0 $-1$ v\u00e0 $3$<\/span><\/span>"}]}],"id_ques":855},{"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":[[["0"]]],"list":[{"point":5,"width":50,"type_input":"","input_hint":"","ques":"T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh ${{x}^{5}}+2{{x}^{3}}=0$ l\u00e0 $S=\\{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\}$","hint":"","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned}&{{x}^{5}}+2{{x}^{3}}=0 \\\\ &\\Leftrightarrow{{x}^{3}}({{x}^{2}}+2)=0 \\\\ &\\Leftrightarrow \\left[\\begin{aligned} & {{x}^{3}}=0 \\\\ & {{x}^{2}}+2=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[\\begin{aligned} & x=0 \\\\ & {{x}^{2}}=-2\\,\\,\\,\\,(\\text {v\u00f4 nghi\u1ec7m, v\u00ec} \\,\\,x^2\\ge 0\\,\\forall x) \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\{0\\}$<br\/><span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o ch\u1ed7 tr\u1ed1ng l\u00e0 $0$<\/span><\/span>"}]}],"id_ques":856},{"time":24,"part":[{"title":"\u0110i\u1ec1n s\u1ed1 th\u00edch h\u1ee3p v\u00e0o ch\u1ed7 tr\u1ed1ng","title_trans":"","temp":"fill_the_blank_random","correct":[[["0"],["1"],["-1"]]],"list":[{"point":5,"width":50,"type_input":"","ques":"T\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh ${{x}^{2017}}=x$ l\u00e0 $S=\\{\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{};\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{};\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\}$","hint":"Chuy\u1ec3n v\u1ebf, \u0111\u1eb7t nh\u00e2n t\u1eed chung v\u00e0 bi\u1ebfn \u0111\u1ed5i ph\u01b0\u01a1ng tr\u00ecnh \u0111\u00e3 cho v\u1ec1 d\u1ea1ng ph\u01b0\u01a1ng tr\u00ecnh t\u00edch.","explain":"<span class='basic_left'>Ta c\u00f3:<br\/>$\\begin{aligned} & {{x}^{2017}}=x \\\\ & \\Leftrightarrow {{x}^{2017}}-x=0 \\\\ &\\Leftrightarrow x\\left( {{x}^{2016}}-1 \\right)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=0 \\\\ & {{x}^{2016}}-1=0 \\\\ \\end{aligned} \\right. \\\\ &\\Leftrightarrow \\left[ \\begin{aligned} & x=0 \\\\ & x=\\pm 1 \\\\ \\end{aligned} \\right. \\\\\\end{aligned}$<br\/>V\u1eady t\u1eadp nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh l\u00e0 $S=\\{0;-1;1\\}$<br\/><span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n v\u00e0o ch\u1ed7 tr\u1ed1ng l\u00e0 $0$ v\u00e0 $1$<\/span><br\/><b>Sai l\u1ea7m c\u1ea7n tr\u00e1nh: <\/b><br\/>C\u00e1ch gi\u1ea3i <span class='basic_green'>sai<\/span>: <br\/>$ {{x}^{2017}}=x \\\\ \\Leftrightarrow {{x}^{2016}}.x=x \\\\ \\Leftrightarrow {{x}^{2016}}=1 \\\\ \\Leftrightarrow x=\\pm 1$<\/span>"}]}],"id_ques":857},{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0110\u00fang ho\u1eb7c Sai","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai19/lv1/img\/10.jpg' \/><\/center>Cho hai bi\u1ec3u th\u1ee9c $A={{x}^{3}}+1$ v\u00e0 $B={{x}^{2}}-1.$<br\/> $x=1$ l\u00e0 m\u1ed9t nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh $A=B$","select":["\u0110\u00fang","Sai"],"hint":"Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh $A=B$, r\u1ed3i k\u1ebft lu\u1eadn.","explain":" <span class='basic_left'>Ta c\u00f3:<br\/> $\\begin{aligned} & A=B \\\\ & \\Leftrightarrow {{x}^{3}}+1={{x}^{2}}-1 \\\\ & \\Leftrightarrow (x+1)({{x}^{2}}-x+1)=(x-1)(x+1) \\\\ & \\Leftrightarrow (x+1)({{x}^{2}}-x+1)-(x-1)(x+1)=0 \\\\ & \\Leftrightarrow (x+1)({{x}^{2}}-x+1-x+1)=0 \\\\ & \\Leftrightarrow (x+1)({{x}^{2}}-2x+2)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x+1=0 \\\\ & {{x}^{2}}-2x+2=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=-1 \\\\ & {{x}^{2}}-2x+2=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=-1 \\\\ & {{x}^{2}}-2x+1+1=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=-1 \\\\ & {{(x-1)}^{2}}+1=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=-1 \\\\ & {{(x-1)}^{2}}=-1 \\,\\,(\\text{v\u00f4 nghi\u1ec7m v\u00ec }(x-1)^2\\ge 0\\,\\forall\\,x ) \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady v\u1edbi $A=B$ th\u00ec $x=-1$<br\/><span class='basic_pink'>V\u1eady kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 Sai.<\/span><br\/><b>C\u00e1ch kh\u00e1c: <\/b>Thay tr\u1ef1c ti\u1ebfp $x=1$ v\u00e0 hai bi\u1ec3u th\u1ee9c $A$ v\u00e0 $B$ r\u1ed3i so s\u00e1nh<\/span>","column":2}]}],"id_ques":858},{"time":24,"part":[{"title":"Kh\u1eb3ng \u0111\u1ecbnh sau \u0110\u00fang ho\u1eb7c Sai","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai19/lv1/img\/10.jpg' \/><\/center>Cho hai bi\u1ec3u th\u1ee9c $A={{\\left( 2x+5 \\right)}^{2}}$ v\u00e0 $B={{\\left( x+3 \\right)}^{2}}$.<br\/> $x=-2$ l\u00e0 m\u1ed9t nghi\u1ec7m c\u1ee7a ph\u01b0\u01a1ng tr\u00ecnh $A=B$","select":["\u0110\u00fang","Sai"],"hint":"Gi\u1ea3i ph\u01b0\u01a1ng tr\u00ecnh $A=B$, r\u1ed3i k\u1ebft lu\u1eadn.","explain":" <span class='basic_left'>Ta c\u00f3:<br\/> $\\begin{aligned} & A=B \\\\ & \\Leftrightarrow {{\\left( 2x+5 \\right)}^{2}}={{\\left( x+3 \\right)}^{2}} \\\\ & \\Leftrightarrow {{\\left( 2x+5 \\right)}^{2}}-{{\\left( x+3 \\right)}^{2}}=0 \\\\ & \\Leftrightarrow \\left[ 2x+5-\\left( x+3 \\right) \\right]\\left[2x+5+\\left( x+3 \\right) \\right]=0 \\\\ & \\Leftrightarrow \\left( x+2 \\right)\\left( 3x+8 \\right)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x+2=0 \\\\ & 3x+8=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=-2 \\\\ & x=\\dfrac{-8}{3} \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady v\u1edbi $A=B$ th\u00ec $x=-2$ ho\u1eb7c $x=\\dfrac{-8}{3}$<br\/><span class='basic_pink'>V\u1eady kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 \u0110\u00fang.<\/span><\/span>","column":2}]}],"id_ques":859},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai19/lv1/img\/10.jpg' \/><\/center>Cho hai bi\u1ec3u th\u1ee9c $A=(3x+4)(x-4) $ v\u00e0 $B=(x-4)(x+2)$. <br\/>T\u00ecm $x$ \u0111\u1ec3 $A$ v\u00e0 $B$ c\u00f3 c\u00f9ng gi\u00e1 tr\u1ecb b\u1eb1ng $0$.","select":["A. $x=-2$","B. $x=4$","C. $x\\in\\left\\{-2;\\dfrac{-4}{3};4\\right\\}$","D. $x=\\dfrac{-4}{3}$"],"hint":"Gi\u00e1 tr\u1ecb $x$ c\u1ea7n t\u00ecm l\u00e0 nghi\u1ec7m 'chung' c\u1ee7a c\u1ea3 hai ph\u01b0\u01a1ng tr\u00ecnh $A=0$ v\u00e0 $B=0$","explain":" <span class='basic_left'>Ta c\u00f3, $A$ v\u00e0 $B$ c\u00f3 c\u00f9ng gi\u00e1 tr\u1ecb b\u1eb1ng $0$. Suy ra: $\\left\\{ \\begin{align} & A=0\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,(1) \\\\ & B=0\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,\\,(2) \\\\ \\end{align} \\right.$<br\/> Gi\u1ea3i (1)<br\/>$\\begin{aligned} & A=0 \\\\ & \\Leftrightarrow (3x+4)(x-4)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & 3x+4=0 \\\\ & x-4=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & 3x=-4 \\\\ & x=4 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=\\dfrac{-4}{3} \\\\ & x=4 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>Gi\u1ea3i (2)<br\/>$\\begin{aligned} & B=0 \\\\ & \\Leftrightarrow (x-4)(x+2)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x-4=0 \\\\ & x+2=0 \\\\ \\end{aligned} \\right. \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & x=4 \\\\ & x=-2 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<br\/>V\u1eady \u0111\u1ec3 $A=B=0$, th\u00ec $x=4$.<br\/><span class='basic_pink'>V\u1eady \u0111\u00e1p \u00e1n \u0111\u00fang l\u00e0 B.<\/span><\/span>","column":2}]}],"id_ques":860}],"lesson":{"save":0,"level":1}}