{"segment":[{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t.<br\/> Kh\u1eb3ng \u0111\u1ecbnh d\u01b0\u1edbi \u0111\u00e2y \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/3.jpg' \/><\/center> Khi ph\u00e2n t\u00edch \u0111a th\u1ee9c $x^2+2xz-y^2+2ty+z^2-t^2$ th\u00e0nh nh\u00e2n t\u1eed th\u00ec c\u00f3 m\u1ed9t nh\u00e2n t\u1eed l\u00e0 $x+z-y+t$ ","select":["\u0110\u00fang","Sai"],"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/><b> B\u01b0\u1edbc 1:<\/b> Ph\u00e2n t\u00edch \u0111a th\u1ee9c theo ph\u01b0\u01a1ng ph\u00e1p nh\u00f3m $(x^2+2xz+z^2)-(y^2-2yt+t^2)$ <br\/><b> B\u01b0\u1edbc 2:<\/b> Ti\u1ebfp t\u1ee5c s\u1eed d\u1ee5ng H\u0110T \u0111\u1ec3 ph\u00e2n t\u00edch.<br\/> <span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'> Ta c\u00f3:<br\/> $\\begin{align} & x^2+2xz-y^2+2ty+z^2-t^2 \\\\ & =(x^2+2xz+z^2)-(y^2-2yt+t^2) \\\\ & =(x+z)^2-(y-t)^2 \\\\ & =(x+z+y-t)(x+z-y+t) \\end{align}$ <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 \u0110\u00fang <\/span>","column":2}]}],"id_ques":581},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t.<br\/> Kh\u1eb3ng \u0111\u1ecbnh d\u01b0\u1edbi \u0111\u00e2y \u0111\u00fang hay sai","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/3.jpg' \/><\/center> Khi ph\u00e2n t\u00edch \u0111a th\u1ee9c $y^2-y-12$ th\u00e0nh nh\u00e2n t\u1eed th\u00ec c\u00f3 m\u1ed9t nh\u00e2n t\u1eed l\u00e0 $y-4$ ","select":["\u0110\u00fang","Sai"],"hint":" Ph\u00e2n t\u00edch \u0111a th\u1ee9c theo ph\u01b0\u01a1ng ph\u00e1p t\u00e1ch $-y=-4y+3y$ ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/><b> B\u01b0\u1edbc 1:<\/b> T\u00e1ch $-y=-4y+3y$ <br\/><b> B\u01b0\u1edbc 2:<\/b> Nh\u00f3m $y^2-4y+3y-12$$=(y^2-4y)+(3y-12)$ <b> <br\/> B\u01b0\u1edbc 3:<\/b> Ti\u1ebfp t\u1ee5c \u0111\u1eb7t nh\u00e2n t\u1eed chung \u0111\u1ec3 ph\u00e2n t\u00edch. <br\/> <span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'> Ta c\u00f3:<br\/> $\\begin{align} & {{y}^{2}}-y-12 \\\\ & ={{y}^{2}}-4y+3y-12 \\\\ & =({{y}^{2}}-4y)+(3y-12) \\\\ & =y\\left( y-4 \\right)+3\\left( y-4 \\right) \\\\ & =\\left( y-4 \\right)\\left( y+3 \\right) \\\\ \\end{align}$ <br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 \u0110\u00fang <\/span>","column":2}]}],"id_ques":582},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/2.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c $A=mx^2+my^2-nx^2-ny^2$ th\u00e0nh nh\u00e2n t\u1eed th\u00ec s\u1ebd c\u00f3 m\u1ed9t nh\u00e2n t\u1eed l\u00e0: ","select":["A. $m-n$ ","B. $x+y$ ","C. $x-y$","D. $(x+y)^2$"],"hint":" Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch nh\u00f3m v\u00e0 \u0111\u1eb7t nh\u00e2n t\u1eed chung. ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch nh\u00f3m <br\/> $A=m{{x}^{2}}+m{{y}^{2}}-n{{x}^{2}}-n{{y}^{2}}$$=\\left( m{{x}^{2}}-n{{x}^{2}} \\right)+\\left( m{{y}^{2}}-n{{y}^{2}} \\right)$ . <br\/><b> B\u01b0\u1edbc 2: <\/b>Ti\u1ebfp t\u1ee5c ph\u00e2n t\u00edch b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3 :<br\/> $\\begin{align} & A=m{{x}^{2}}+m{{y}^{2}}-n{{x}^{2}}-n{{y}^{2}} \\\\ & =\\left( m{{x}^{2}}-n{{x}^{2}} \\right)+\\left( m{{y}^{2}}-n{{y}^{2}} \\right) \\\\ & ={{x}^{2}}\\left( m-n \\right)+{{y}^{2}}\\left( m-n \\right) \\\\ & =\\left( m-n \\right)\\left( {{x}^{2}}+{{y}^{2}} \\right) \\\\ \\end{align}$ <span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A<\/span>","column":2}]}],"id_ques":583},{"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/bai7/lv1/img\/2.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c $A=a^3+a^2b-a^2c-abc$ th\u00e0nh nh\u00e2n t\u1eed th\u00ec s\u1ebd c\u00f3 m\u1ed9t nh\u00e2n t\u1eed l\u00e0: ","select":["A. $a+c$ ","B. $a-c$ ","C. $a-b$","D. $a^2-2$"],"hint":" Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch nh\u00f3m v\u00e0 \u0111\u1eb7t nh\u00e2n t\u1eed chung. ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch nh\u00f3m $A=a^3+a^2b-a^2c-abc$$=(a^3+a^2b)-(a^2c+abc)$ . <br\/><b> B\u01b0\u1edbc 2: <\/b>Ti\u1ebfp t\u1ee5c ph\u00e2n t\u00edch b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3 :<br\/> $\\begin{align} & A={{a}^{3}}+{{a}^{2}}b-{{a}^{2}}c-abc \\\\ & =\\left( {{a}^{3}}+{{a}^{2}}b \\right)-\\left( {{a}^{2}}c+abc \\right) \\\\ & ={{a}^{2}}\\left( a+b \\right)-ac\\left( a+b \\right) \\\\&= (a^2 - ac) (a + b)\\\\ & =a\\left( a+b \\right)\\left( a-c \\right) \\\\ \\end{align}$ <span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B<\/span>","column":2}]}],"id_ques":584},{"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/bai7/lv1/img\/16.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c $A=5x^2+6xy+y^2$ th\u00e0nh nh\u00e2n t\u1eed th\u00ec s\u1ebd c\u00f3 m\u1ed9t nh\u00e2n t\u1eed l\u00e0: ","select":["A. $x+y$ ","B. $x-y$ ","C. $5x-y$","D. $x+5y $"],"hint":" Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch t\u00e1ch v\u00e0 \u0111\u1eb7t nh\u00e2n t\u1eed chung. ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch t\u00e1ch $6xy=5xy+xy$ . <br\/><b> B\u01b0\u1edbc 2: <\/b>Ti\u1ebfp t\u1ee5c ph\u00e2n t\u00edch b\u1eb1ng c\u00e1ch nh\u00f3m r\u1ed3i \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3 :<br\/> $\\begin{align} & A=5{{x}^{2}}+6xy+{{y}^{2}} \\\\ & =5{{x}^{2}}+5xy+xy+{{y}^{2}} \\\\ & =5x\\left( x+y \\right)+y\\left( x+y \\right) \\\\ & =\\left( x+y \\right)\\left( 5x+y \\right) \\\\ \\end{align}$ <span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A<\/span>","column":2}]}],"id_ques":585},{"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/bai7/lv1/img\/16.jpg' \/><\/center> \u0110a th\u1ee9c $A=x^3-3x^2+4x-2$ c\u00f3 gi\u00e1 tr\u1ecb b\u1eb1ng 0 khi:","select":["A. $x=1$ ","B. $x=2$ ","C. $x=3$","D. $x=4$"],"hint":" Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed <br\/> T\u00ecm \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 A = 0. N\u1ebfu a.b = 0 th\u00ec ho\u1eb7c a = 0 ho\u1eb7c b = 0.","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed <br\/> $A={{x}^{3}}-3{{x}^{2}}+4x-2 $$={{x}^{3}}-3{{x}^{2}}+3x-1+x-1 $$=\\left( {{x}^{3}}-3{{x}^{2}}+3x-1 \\right)+\\left( x-1 \\right)$. <br\/><b> B\u01b0\u1edbc 2: <\/b>Ti\u1ebfp t\u1ee5c ph\u00e2n t\u00edch b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/> <b> B\u01b0\u1edbc 3:<\/b> T\u00ecm \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 A = 0<br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3 :<br\/> $\\begin{align} & A={{x}^{3}}-3{{x}^{2}}+4x-2 \\\\ & ={{x}^{3}}-3{{x}^{2}}+3x-1+x-1 \\\\ & =\\left( {{x}^{3}}-3{{x}^{2}}+3x-1 \\right)+\\left( x-1 \\right) \\\\ & ={{\\left( x-1 \\right)}^{3}}+\\left( x-1 \\right) \\\\ & =\\left( x-1 \\right)\\left[ {{\\left( x-1 \\right)}^{2}}+1 \\right] \\\\ & Do\\,\\,\\,{{\\left( x-1 \\right)}^{2}}+1\\,\\,\\,>0 (\\forall x) \\\\ & \\Rightarrow A=0 \\Leftrightarrow x-1=0\\,\\,\\Leftrightarrow x=1 \\\\ \\end{align}$ <span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A<\/span>","column":2}]}],"id_ques":586},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/13.jpg' \/><\/center> \u0110a th\u1ee9c $A=x^2+x+y^2+y+2xy$ c\u00f3 gi\u00e1 tr\u1ecb b\u1eb1ng 0 th\u00ec m\u1ed1i li\u00ean h\u1ec7 gi\u1eefa $x$ v\u00e0 $y$ l\u00e0:","select":["A. $x+y=1$ ","B. $x=y =1$ ","C. $x=y=2$","D. $x+y=0$ ho\u1eb7c $x+y+1=0$"],"hint":" Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed <br\/> T\u00ecm \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 $A = 0$. N\u1ebfu $a.b = 0$ th\u00ec ho\u1eb7c $a = 0$ ho\u1eb7c $b = 0$.","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed <br\/>$A={{x}^{2}}+x+{{y}^{2}}+y+2xy$$=\\left( {{x}^{2}}+2xy+{{y}^{2}} \\right)+\\left( x+y \\right)$$={{\\left( x+y \\right)}^{2}}+\\left( x+y \\right)$. <br\/><b> B\u01b0\u1edbc 2: <\/b>Ph\u00e2n t\u00edch b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/> <b> B\u01b0\u1edbc 3:<\/b> T\u00ecm \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 $A = 0$. N\u1ebfu $a.b = 0$ th\u00ec ho\u1eb7c $a = 0$ ho\u1eb7c $b = 0$.<br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3 :<br\/> $\\begin{align} & A={{x}^{2}}+x+{{y}^{2}}+y+2xy \\\\ & =\\left( {{x}^{2}}+2xy+{{y}^{2}} \\right)+\\left( x+y \\right) \\\\ & ={{\\left( x+y \\right)}^{2}}+\\left( x+y \\right) \\\\ & =\\left( x+y \\right)\\left( x+y+1 \\right) \\\\ \\end{align}$ <br\/>\u0110\u1ec3 $A = 0$ th\u00ec: $\\left[ \\begin{align} & x+y=0 \\\\ & x+y+1=0 \\\\ \\end{align} \\right.$ <span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D<\/span>","column":2}]}],"id_ques":587},{"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/bai7/lv1/img\/13.jpg' \/><\/center> \u0110a th\u1ee9c $A=ax^2+ay-bx^2-by$ c\u00f3 gi\u00e1 tr\u1ecb b\u1eb1ng 0 th\u00ec m\u1ed1i li\u00ean h\u1ec7 gi\u1eefa $x, y, a$ v\u00e0 $b$ l\u00e0:","select":["A. $a = -b$ ","B. $ax^2=y$ ","C. $a = b$ ho\u1eb7c $x^2=-y$ v\u1edbi $y < 0$.","D. $a = b = x = y $"],"hint":" Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p nh\u00f3m<br\/> T\u00ecm \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 $A = 0$. N\u1ebfu $a.b = 0$ th\u00ec ho\u1eb7c $a = 0$ ho\u1eb7c $b = 0$.","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed theo ph\u01b0\u01a1ng ph\u00e1p \u0111\u1eb7t nh\u00e2n t\u1eed chung. <br\/> <b> B\u01b0\u1edbc 2: <\/b>Ph\u00e2n t\u00edch b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/> <b> B\u01b0\u1edbc 3:<\/b> T\u00ecm \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 $A = 0$. N\u1ebfu $a.b = 0$ th\u00ec ho\u1eb7c $a = 0$ ho\u1eb7c $b = 0$.<br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3 :<br\/> $\\begin{align} & A=a{{x}^{2}}+ay-b{{x}^{2}}-by \\\\ & =\\left( a\\,{{x}^{2}}+ay \\right)-\\left( b{{x}^{2}}+by \\right) \\\\ & =a\\left( {{x}^{2}}+y \\right)-b\\left( {{x}^{2}}+y \\right) \\\\ & =\\left( {{x}^{2}}+y \\right)\\left( a-b \\right) \\\\ \\end{align}$ <br\/>\u0110\u1ec3 $A = 0$ th\u00ec $\\left[ \\begin{aligned} & a-b=0 \\\\ & {{x}^{2}}+y=0 \\\\ \\end{aligned} \\right.\\Leftrightarrow \\left[ \\begin{aligned} & a=b \\\\ & {{x}^{2}}=-y\\,\\,\\,\\,\\left( \\,y<0 \\right) \\\\ \\end{aligned} \\right.$ <span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C<\/span>","column":2}]}],"id_ques":588},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["14"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/12.jpg' \/><\/center> Gi\u00e1 tr\u1ecb c\u1ee7a \u0111a th\u1ee9c $x^2+x-6$ v\u1edbi $x = -5$ l\u00e0 _input_","hint":"C\u00e1ch 1: Thay tr\u1ef1c ti\u1ebfp $x = -5$ v\u00e0o \u0111a th\u1ee9c \u0111\u1ec3 t\u00ednh.<br\/> C\u00e1ch 2: Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed <br\/> Thay $x = -5$ v\u00e0o \u0111a th\u1ee9c \u0111\u1ec3 t\u00ednh gi\u00e1 tr\u1ecb.","explain":"<span class='basic_left'><b> C\u00e1ch 1:<\/b> Thay $x = -5$ v\u00e0o \u0111a th\u1ee9c: $x^2+x-6$$=(-5)^2+(-5)-6=25-5-6=14$<br\/> <b> C\u00e1ch 2:<\/b> Ta c\u00f3: <br\/> $x^2+x-6=x^2-2x+3x-6$$=(x^2-2x)+(3x-6)$$=x(x-2)+3(x-2)$$=(x-2)(x+3)$ <br\/>Thay $x = -5$, ta \u0111\u01b0\u1ee3c:<br\/>$(x-2)(x+3)$$=(-5-2)(-5+3)=-7.(-2)=14$ <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $14$ <\/span><\/span> "}]}],"id_ques":589},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["-9"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<span class='basic_left'><center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/11.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed r\u1ed3i th\u1ef1c hi\u1ec7n t\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a \u0111a th\u1ee9c $2xy-x^2-y^2+16$ <br\/>v\u1edbi $x = -2; y = 3$<br\/>Gi\u00e1 tr\u1ecb c\u1ee7a \u0111a th\u1ee9c l\u00e0: _input_<\/span>","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> Nh\u00f3m c\u00e1c h\u1ea1ng t\u1eed c\u1ee7a \u0111a th\u1ee9c, ta \u0111\u01b0\u1ee3c: $2xy-x^2-y^2+16$$=-(x^2-2xy+y^2)+16$ $=4^2-(x-y)^2$.<br\/> <b>B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch d\u00f9ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c.<br\/> <b> B\u01b0\u1edbc 3:<\/b> Thay $x = -2; y = 3$ v\u00e0o \u0111a th\u1ee9c \u0111\u1ec3 t\u00ednh gi\u00e1 tr\u1ecb.<br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/> Ta c\u00f3: <br\/> $\\begin{align} & 2xy-{{x}^{2}}-{{y}^{2}}+16 \\\\ & =-({{x}^{2}}-2xy+{{y}^{2}})+16 \\\\ & ={{4}^{2}}-{{(x-y)}^{2}} \\\\ & =\\left( 2+x-y \\right)\\left( 2-x+y \\right) \\\\ \\end{align}$ <br\/>Thay $x = -2; y = 3$, ta \u0111\u01b0\u1ee3c:<br\/>$\\left( 4+x-y \\right)\\left( 4-x+y \\right)=\\left( 4-2-3 \\right)\\left( 4+2+3 \\right)=\\left( -1 \\right).9=-9$ <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $-9$ <\/span><\/span> "}]}],"id_ques":590},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["0"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/10.jpg' \/><\/center> Gi\u00e1 tr\u1ecb c\u1ee7a \u0111a th\u1ee9c $x^2-3x+2$ v\u1edbi $x = 1$ l\u00e0 _input_","hint":"C\u00e1ch 1: Thay tr\u1ef1c ti\u1ebfp $x = 1$ v\u00e0o \u0111a th\u1ee9c \u0111\u1ec3 t\u00ednh.<br\/> C\u00e1ch 2: Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed <br\/> Thay $x = 1$ v\u00e0o \u0111a th\u1ee9c \u0111\u1ec3 t\u00ednh gi\u00e1 tr\u1ecb.","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/><b>C\u00e1ch 1:<\/b> Thay tr\u1ef1c ti\u1ebfp $x = 1$ v\u00e0o \u0111a th\u1ee9c \u0111\u1ec3 t\u00ednh.<br\/><b> C\u00e1ch 2:<\/b><br\/> <b> B\u01b0\u1edbc 1: <\/b> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed $x^2-3x+2$$=x^2-x-2x+2$$=(x^2-x)-(2x-2)$.<br\/> <b>B\u01b0\u1edbc 2:<\/b> Ti\u1ebfp t\u1ee5c ph\u00e2n t\u00edch th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/> <b> B\u01b0\u1edbc 3:<\/b> Thay $x = 1$ v\u00e0o \u0111a th\u1ee9c \u0111\u1ec3 t\u00ednh gi\u00e1 tr\u1ecb.<br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/><b> C\u00e1ch 1:<\/b> Thay $x = 1$ v\u00e0o \u0111a th\u1ee9c: $x^2-3x+2=1^2-3.1+2$$=1-3+2=0$<br\/> <b> C\u00e1ch 2:<\/b> Ta c\u00f3: <br\/> $x^2-3x+2 \\\\ =x^2-x-2x+2 \\\\ =(x^2-x)-(2x-2) \\\\ =x(x-1)-2(x-1) \\\\ =(x-1)(x-2)$ <br\/>Thay $x = 1$, ta \u0111\u01b0\u1ee3c:<br\/>$(x-1)(x-2)$$=(1-1)(2-1)=0$ <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $0$ <\/span><\/span> "}]}],"id_ques":591},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"select":["A. $\\left[\\begin{array}{l}{x=\\dfrac{5}{2}} \\\\ {x = \\dfrac{1}{2}}\\end{array}\\right.$","B. $\\left[\\begin{array}{l}{x=\\dfrac{7}{2}} \\\\ {x = \\dfrac{-1}{2}}\\end{array}\\right.$","C. $\\left[\\begin{array}{l}{x=\\dfrac{5}{2}} \\\\ {x = \\dfrac{-1}{2}}\\end{array}\\right.$"],"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/9.jpg' \/><\/center> Bi\u1ebft $4x^2-12x-7=0$, gi\u00e1 tr\u1ecb $x =?$","hint":"Ph\u00e2n t\u00edch v\u1ebf tr\u00e1i th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch t\u00e1ch r\u1ed3i nh\u00f3m<br\/> N\u1ebfu $a.b = 0$ th\u00ec $a = 0$ ho\u1eb7c $b = 0$. ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b>B\u01b0\u1edbc 1:<\/b> Ph\u00e2n t\u00edch v\u1ebf tr\u00e1i th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch t\u00e1ch r\u1ed3i nh\u00f3m: <br\/> $4x^2-12x-7=4x^2-12x+9-16$$=(4x^2-12x+9)-16$.<br\/> <b> B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch $(4x^2-12x+9)-16$ th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch d\u00f9ng H\u0110T.<br\/> <b> B\u01b0\u1edbc 3: <\/b> T\u00ecm x. <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/> Ta c\u00f3:<br\/> $\\begin{aligned} & 4x^2-12x-7=0 \\\\ & \\Leftrightarrow 4x^2-12x+9-16=0 \\\\ & \\Leftrightarrow (4x^2-12x+9)-16=0 \\\\ & \\Leftrightarrow (2x-3)^2-4^2=0 \\\\ & \\Leftrightarrow (2x-3+4)(2x-3-4)=0 \\\\ & \\Leftrightarrow (2x+1)(2x-7)=0 \\\\ & \\Rightarrow \\left[ \\begin{aligned} & 2x+1=0 \\\\ & 2x-7=0 \\\\ \\end{aligned} \\right.\\Leftrightarrow \\left[ \\begin{aligned} & x=\\dfrac{-1}{2} \\\\ & x=\\dfrac{7}{2} \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$<\/span> "}]}],"id_ques":592},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank_random","correct":[[["5"],["4"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/8.jpg' \/><\/center> Bi\u1ebft $x^2-9x+20=0$, khi \u0111\u00f3 $\\left[ \\begin{align} & x= \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\\\ & x=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\\\ \\end{align} \\right.$ ","hint":"Ph\u00e2n t\u00edch v\u1ebf tr\u00e1i th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch t\u00e1ch r\u1ed3i nh\u00f3m<br\/> N\u1ebfu $a.b = 0$ th\u00ec $a = 0$ ho\u1eb7c $b = 0$. ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/> <b>B\u01b0\u1edbc 1:<\/b> Ph\u00e2n t\u00edch v\u1ebf tr\u00e1i th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch t\u00e1ch r\u1ed3i nh\u00f3m: <br\/> $x^2-9x+20=x^2-5x-4x+20$$=(x^2-5x)-(4x-20)$.<br\/> <b> B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch $(x^2-5x)-(4x-20)$ th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/> <b> B\u01b0\u1edbc 3: <\/b> T\u00ecm $x$. <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/> Ta c\u00f3:<br\/> $\\begin{aligned} & x^2-9x+20=0 \\\\ & \\Leftrightarrow x^2-5x-4x+20=0 \\\\ & \\Leftrightarrow (x^2-5x)-(4x-20)=0 \\\\ & \\Leftrightarrow x(x-5)-4(x-5)=0 \\\\ & \\Leftrightarrow (x-5)(x-4)=0 \\\\ & \\Rightarrow \\left[ \\begin{aligned} & x-5=0 \\\\ & x-4=0 \\\\ \\end{aligned} \\right.\\Leftrightarrow \\left[ \\begin{aligned} & x=5 \\\\ & x=4 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $5$ v\u00e0 $4$<\/span><\/span> "}]}],"id_ques":593},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank_random","correct":[[["3"],["-6"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/8.jpg' \/><\/center> Bi\u1ebft $x^2+3x-18=0$, khi \u0111\u00f3 $\\left[ \\begin{align} & x= \\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}\\\\ & x=\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{} \\\\ \\end{align} \\right.$ ","hint":"Ph\u00e2n t\u00edch v\u1ebf tr\u00e1i th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch t\u00e1ch r\u1ed3i nh\u00f3m<br\/> N\u1ebfu $a.b = 0$ th\u00ec $a = 0$ ho\u1eb7c $b = 0$. ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/> <b>B\u01b0\u1edbc 1:<\/b> Ph\u00e2n t\u00edch v\u1ebf tr\u00e1i th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch t\u00e1ch r\u1ed3i nh\u00f3m: <br\/> $x^2+3x-18=x^2-3x+6x-18$$=(x^2-3x)+(6x-18)$.<br\/> <b> B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch $(x^2-3x)+(6x-18)$ th\u00e0nh nh\u00e2n t\u1eed b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/> <b> B\u01b0\u1edbc 3: <\/b> T\u00ecm $x$. <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/> Ta c\u00f3:<br\/> $\\begin{aligned} & x^2+3x-18=0 \\\\ & \\Leftrightarrow x^2-3x+6x-18=0 \\\\ & \\Leftrightarrow (x^2-3x)+(6x-18)=0 \\\\ & \\Leftrightarrow x(x-3)+6(x-3)=0 \\\\ & \\Leftrightarrow (x-3)(x+6)=0 \\\\ & \\Rightarrow \\left[ \\begin{aligned} & x-3=0 \\\\ & x+6=0 \\\\ \\end{aligned} \\right.\\Leftrightarrow \\left[ \\begin{aligned} & x=3 \\\\ & x=-6 \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $3$ v\u00e0 $-6$ <\/span><\/span> "}]}],"id_ques":594},{"time":24,"part":[{"title":"\u0110i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng trong k\u1ebft qu\u1ea3 ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed","title_trans":"","temp":"fill_the_blank_random","correct":[[["x+4","4+x"],["x+5","5+x"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/5.jpg' \/><\/center> $x^2+9x+20$$=(\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})\\times (\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})$","hint":"Ta ph\u00e2n t\u00edch b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p t\u00e1ch r\u1ed3i nh\u00f3m <br\/>Ph\u00e2n t\u00edch ti\u1ebfp b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/><b> B\u01b0\u1edbc 1:<\/b> Ta ph\u00e2n t\u00edch b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p t\u00e1ch r\u1ed3i nh\u00f3m: <br\/> $x^2+9x+20=x^2+5x+4x+20$$=(x^2+5x)+(4x+20)$.<br\/> <b> B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch ti\u1ebfp theo ph\u01b0\u01a1ng ph\u00e1p \u0111\u1eb7t nh\u00e2n t\u1eed chung. <br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $\\begin{align} & {{x}^{2}}+9x+20 \\\\ & ={{x}^{2}}+5x+4x+20 \\\\ & =\\left( {{x}^{2}}+5x \\right)+\\left( 4x+20 \\right) \\\\ & =x\\left( x+5 \\right)+4\\left( x+5 \\right) \\\\ & =\\left( x+5 \\right)\\left( x+4 \\right) \\\\ \\end{align}$<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n c\u1ea7n \u0111i\u1ec1n l\u00e0 $x + 5$ v\u00e0 $x + 4$<\/span>"}]}],"id_ques":595},{"time":24,"part":[{"title":"\u0110i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng trong k\u1ebft qu\u1ea3 ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed","title_trans":"","temp":"fill_the_blank_random","correct":[[["x+3","3+x"],["x-4"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/5.jpg' \/><\/center> $x^2-x-12$$=(\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})\\times (\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})$","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/><b> B\u01b0\u1edbc 1:<\/b> Ta ph\u00e2n t\u00edch b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p t\u00e1ch r\u1ed3i nh\u00f3m: $x^2-x-12=x^2-4x+3x-12$$=(x^2-4x)+(3x-12)$.<br\/> <b> B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch ti\u1ebfp theo ph\u01b0\u01a1ng ph\u00e1p \u0111\u1eb7t nh\u00e2n t\u1eed chung. <br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $\\begin{align} & {{x}^{2}}-x-12 \\\\ & ={{x}^{2}}-4x+3x-12 \\\\ & =\\left( {{x}^{2}}-4x \\right)+\\left( 3x-12 \\right) \\\\ & =x\\left( x-4 \\right)+3\\left( x-4 \\right) \\\\ & =\\left( x-4 \\right)\\left( x+3 \\right) \\\\ \\end{align}$<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n c\u1ea7n \u0111i\u1ec1n l\u00e0 $x - 4$ v\u00e0 $x + 3$<\/span>"}]}],"id_ques":596},{"time":24,"part":[{"title":"\u0110i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng trong k\u1ebft qu\u1ea3 ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed","title_trans":"","temp":"fill_the_blank_random","correct":[[["x"],["3"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/5.jpg' \/><\/center> $x^2+5x+6$$=(x+2)(\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}+\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})$","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/><b> B\u01b0\u1edbc 1:<\/b> Ta ph\u00e2n t\u00edch b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p t\u00e1ch r\u1ed3i nh\u00f3m: $x^2+5x+6=x^2+2x+3x+6$$=(x^2+2x)+(3x+6)$.<br\/> <b> B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch ti\u1ebfp theo ph\u01b0\u01a1ng ph\u00e1p \u0111\u1eb7t nh\u00e2n t\u1eed chung. <br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $\\begin{align} & {{x}^{2}}+5x+6 \\\\ & ={{x}^{2}}+2x+3x+6 \\\\ & =\\left( {{x}^{2}}+2x \\right)+\\left( 3x+6 \\right) \\\\ & =x\\left( x+2 \\right)+3\\left( x+2 \\right) \\\\ & =\\left( x+2 \\right)\\left( x+3 \\right) \\\\ \\end{align}$<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n c\u1ea7n \u0111i\u1ec1n l\u00e0 $x$ v\u00e0 $3$<\/span>"}]}],"id_ques":597},{"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":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/4.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c $x^2+x-20$ th\u00e0nh nh\u00e2n t\u1eed, ta \u0111\u01b0\u1ee3c:","select":["A. $(x+5)(x+4)$ ","B. $(x-5)(x-4)$ ","C. $(x-5)(x+4)$","D. $(x+5)(x-4)$"],"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/>Ta ph\u00e2n t\u00edch b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p t\u00e1ch r\u1ed3i nh\u00f3m: $x^2+x-20=x^2-4x+5x-20$$=(x^2-4x)+(5x-20)$ <br\/>Ph\u00e2n t\u00edch ti\u1ebfp b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $\\begin{align} & {{x}^{2}}+x-20 \\\\ & ={{x}^{2}}-4x+5x-20 \\\\ & =\\left( {{x}^{2}}-4x \\right)+\\left( 5x-20 \\right) \\\\ & =x\\left( x-4 \\right)+5\\left( x-4 \\right) \\\\ & =\\left( x-4 \\right)\\left( x+5 \\right) \\\\ \\end{align}$<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D<\/span>","column":2}]}],"id_ques":598},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai7/lv1/img\/3.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c $x^2+x-12$ th\u00e0nh nh\u00e2n t\u1eed, ta \u0111\u01b0\u1ee3c:","select":["A. $(x+3)(x+4)$ ","B. $(x-3)(x+4)$ ","C. $(x+3)(x-4)$","D. $(x-3)(x-4)$"],"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/>Ta ph\u00e2n t\u00edch b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p t\u00e1ch r\u1ed3i nh\u00f3m: $x^2+x-12=x^2+4x-3x-12$$=(x^2+4x)-(3x+12)$ <br\/>Ph\u00e2n t\u00edch ti\u1ebfp b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $\\begin{align} & {{x}^{2}}+x-12 \\\\ & ={{x}^{2}}+4x-3x-12 \\\\ & =\\left( {{x}^{2}}+4x \\right)-\\left( 3x+12 \\right) \\\\ & =x\\left( x+4 \\right)-3\\left( x+4 \\right) \\\\ & =\\left( x+4 \\right)\\left( x-3 \\right) \\\\ \\end{align}$<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B<\/span>","column":2}]}],"id_ques":599},{"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/bai7/lv1/img\/2.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c $x^2-5x+6$ th\u00e0nh nh\u00e2n t\u1eed, ta \u0111\u01b0\u1ee3c:","select":["A. $(x-3)(x-2)$ ","B. $(x-3)(x+2)$ ","C. $(x+3)(x-2)$","D. $(x+3)(x+2)$"],"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/>Ta ph\u00e2n t\u00edch b\u1eb1ng ph\u01b0\u01a1ng ph\u00e1p t\u00e1ch r\u1ed3i nh\u00f3m: $x^2-5x+6=x^2-2x-3x+6$$=(x^2-2x)-(3x-6)$ <br\/>Ph\u00e2n t\u00edch ti\u1ebfp b\u1eb1ng c\u00e1ch \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $\\begin{align} & {{x}^{2}}-5x+6 \\\\ & ={{x}^{2}}-2x-3x+6 \\\\ & =\\left( {{x}^{2}}-2x \\right)-\\left( 3x-6 \\right) \\\\ & =x\\left( x-2 \\right)-3\\left( x-2 \\right) \\\\ & =\\left( x-2 \\right)\\left( x-3 \\right) \\\\ \\end{align}$<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A<\/span>","column":2}]}],"id_ques":600}],"lesson":{"save":0,"level":1}}