{"segment":[{"time":4,"part":[{"time":24,"title":"N\u1ed1i c\u00e1c \u00fd \u1edf c\u1ed9t b\u00ean tr\u00e1i v\u1edbi c\u1ed9t b\u00ean ph\u1ea3i \u0111\u1ec3 \u0111\u01b0\u1ee3c c\u00e2u ho\u00e0n ch\u1ec9nh","title_trans":"N\u1ed1i c\u00e1c \u00fd \u1edf c\u1ed9t b\u00ean tr\u00e1i v\u1edbi c\u1ed9t b\u00ean ph\u1ea3i \u0111\u1ec3 \u0111\u01b0\u1ee3c c\u00e2u ho\u00e0n ch\u1ec9nh","audio":"","temp":"matching","correct":[["3","2","1"]],"list":[{"point":5,"image":"https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/9.jpg","left":["$1-x^2$","$4x^2-4$","$x^2+2x+1$"],"right":["$(x+1)^2$","$4(x+1)(x-1)$","$(1-x)(1+x)$"],"top":100,"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Ta ph\u00e2n t\u00edch c\u00e1c \u0111a th\u1ee9c \u1edf c\u1ed9t tr\u00e1i th\u00e0nh nh\u00e2n t\u1eed theo ph\u01b0\u01a1ng ph\u00e1p d\u00f9ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c v\u00e0 \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/>T\u1eeb \u0111\u00f3 so s\u00e1nh c\u00e1c \u0111\u00e1p \u00e1n b\u00ean c\u1ed9t ph\u1ea3i \u0111\u1ec3 n\u1ed1i.<br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>+ Ta c\u00f3: $1-x^2=(1-x)(1+x)$<br\/> + Ta c\u00f3: $4x^2-4=4(x^2-1)=4(x+1)(x-1)$<br\/> $x^2+2x+1=(x+1)^2$ <br\/> <span class='basic_pink'> K\u1ebft lu\u1eadn:<br\/> N\u1ed1i $1$ v\u1edbi $(1-x)(1+x)$<br\/> N\u1ed1i $2$ v\u1edbi $4(x+1)(x-1)$<br\/> N\u1ed1i $3$ v\u1edbi $(x+1)^2$.<\/span> <\/span>"}]}],"id_ques":531},{"time":24,"part":[{"time":3,"title":"N\u1ed1i c\u00e1c \u00fd \u1edf c\u1ed9t b\u00ean tr\u00e1i v\u1edbi c\u1ed9t b\u00ean ph\u1ea3i \u0111\u1ec3 \u0111\u01b0\u1ee3c c\u00e2u ho\u00e0n ch\u1ec9nh","title_trans":"N\u1ed1i c\u00e1c \u00fd \u1edf c\u1ed9t b\u00ean tr\u00e1i v\u1edbi c\u1ed9t b\u00ean ph\u1ea3i \u0111\u1ec3 \u0111\u01b0\u1ee3c c\u00e2u ho\u00e0n ch\u1ec9nh","audio":"","temp":"matching","correct":[["1","3","2"]],"list":[{"point":5,"image":"https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/9.jpg","left":["$8x^3-12x^2+6x-1$","$(2-3x)(4+6x+9x^2)$","$(1-x)(1+x+x^2)$"],"right":["$(2x-1)^3$","$1-x^3$","$8-27x^3$"],"top":100,"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>S\u1eed d\u1ee5ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c \u0111\u1ec3 thu g\u1ecdn c\u00e1c \u0111a th\u1ee9c \u1edf c\u1ed9t tr\u00e1i<br\/>T\u1eeb \u0111\u00f3 so s\u00e1nh c\u00e1c \u0111\u00e1p \u00e1n b\u00ean c\u1ed9t ph\u1ea3i \u0111\u1ec3 n\u1ed1i.<br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>+ Ta c\u00f3: $8x^3-12x^2+6x-1=(2x-1)^3$<br\/> + Ta c\u00f3: $(2-3x)(4+6x+9x^2)=2^3-(3x)^3=8-27x^3$<br\/> $(1-x)(1+x+x^2)=1-x^3$ <br\/> <span class='basic_pink'>K\u1ebft lu\u1eadn:<br\/> N\u1ed1i $1$ v\u1edbi $(2x-1)^3$<br\/> N\u1ed1i $2$ v\u1edbi $8-27x^3$<br\/> N\u1ed1i $3$ v\u1edbi $1-x^3$.<\/span> <\/span>"}]}],"id_ques":532},{"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/bai6/lv1/img\/9.jpg' \/><\/center> Bi\u1ec3u th\u1ee9c $A=12y-27y^3$ c\u00f3 gi\u00e1 tr\u1ecb b\u1eb1ng $0$ khi:","select":["A. $y=0;\\pm\\dfrac{1}{3}$ ","B. $y=0;\\pm\\dfrac{1}{9}$ ","C. $y=0;\\pm\\dfrac{4}{9}$","D. $y=0;\\pm\\dfrac{2}{3}$"],"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 bi\u1ec3u th\u1ee9c $A$ th\u00e0nh nh\u00e2n t\u1eed theo ph\u01b0\u01a1ng ph\u00e1p \u0111\u1eb7t nh\u00e2n t\u1eed chung $12y-27y^3=3y(4-9y^2)$ <br\/> <b> B\u01b0\u1edbc 2:<\/b> T\u00ecm \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 $A = 0$. N\u1ebfu $a.b = 0$ th\u00ec $a = 0$ ho\u1eb7c $b = 0$.<br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3 :<br\/> $A=12y-27{{y}^{3}}=3y\\left( 4-9{{y}^{2}} \\right)=3y\\left( 2-3y \\right)\\left( 2+3y \\right)$ <br\/>\u0110\u1ec3 A = 0 th\u00ec:<br\/>$\\begin{aligned} & 3y\\left( 2-3y \\right)\\left( 2+3y \\right)=0 \\\\ & \\Leftrightarrow \\left[ \\begin{aligned} & 3y=0 \\\\ & 2-3y=0 \\\\ & 2+3y=0 \\\\ \\end{aligned} \\right.\\Leftrightarrow \\left[ \\begin{aligned} & y=0 \\\\ & y=\\dfrac{2}{3} \\\\ & y=-\\dfrac{2}{3} \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D.<\/span>","column":2}]}],"id_ques":533},{"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/bai6/lv1/img\/16.jpg' \/><\/center> Bi\u1ec3u th\u1ee9c $A=40x^2+15xz+8x+3z$ c\u00f3 gi\u00e1 tr\u1ecb b\u1eb1ng $0$ khi:","select":["A. $x = 5$ ho\u1eb7c $z = 3$ ","B. $2x = z$ ho\u1eb7c $5x = z$ ","C. $x = -\\dfrac{1}{5}$ ho\u1eb7c $z = \\dfrac{8}{15}$","D. $z = \\dfrac{-8}{3}.x$ ho\u1eb7c $x = -\\dfrac{1}{5}$"],"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 $40x^2+15xz+8x+3z=(40x^2+15xz)+(8x+3z)$<br\/> <b> B\u01b0\u1edbc 2:<\/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 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'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3 :<br\/> $A=40x^2+15xz+8x+3z \\\\ =(40x^2+15xz)+(8x+3z) \\\\ =5x(8x+3z)+(8x+3z) \\\\ =(8x+3z)(5x+1)$ .<br\/> \u0110\u1ec3 $A = 0$ t\u1ee9c l\u00e0 <br\/>$\\begin{aligned} & (8x+3z)(5x+1)=0 \\\\ & \\Rightarrow \\left[ \\begin{aligned} & 8x+3z=0 \\\\ & 5x+1=0 \\\\ \\end{aligned} \\right.\\Leftrightarrow \\left[ \\begin{aligned} & z = \\dfrac{-8}{3}.x \\\\ & x=-\\dfrac{1}{5} \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D.<\/span>","column":2}]}],"id_ques":534},{"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/bai6/lv1/img\/16.jpg' \/><\/center> Bi\u1ec3u th\u1ee9c $A=9y^2-4z^2$ c\u00f3 gi\u00e1 tr\u1ecb b\u1eb1ng $0$ khi:","select":["A. $3y=2z$ ho\u1eb7c $3y=-2z$ ","B. $3y=4z$ ho\u1eb7c $3y=4z$ ","C. $9y=2z$ ho\u1eb7c $9y=-2z$","D. $9y=4z$ ho\u1eb7c $9y=-4z$"],"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 th\u00e0nh nh\u00e2n t\u1eed theo ph\u01b0\u01a1ng ph\u00e1p h\u1eb1ng \u0111\u1eb3ng th\u1ee9c $9y^2-4z^2=(3y)^2-(2z)^2$ <br\/> <b> B\u01b0\u1edbc 2:<\/b> T\u00ecm \u0111i\u1ec1u ki\u1ec7n \u0111\u1ec3 $A = 0$. N\u1ebfu $a.b = 0$ th\u00ec $a = 0$ ho\u1eb7c $b = 0$.<br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3 :<br\/> $A=9y^2-4z^2=(3y)^2-(2z)^2 =(3y+2z)(3y-2z)$ <br\/>\u0110\u1ec3 $A = 0$ t\u1ee9c l\u00e0:<br\/>$\\begin{aligned} & \\text{(3y+2z)(3y-2z)}=0 \\\\ & \\Rightarrow \\left[ \\begin{aligned} & 3y+2z=0 \\\\ & 3y-2z=0 \\\\ \\end{aligned} \\right.\\Leftrightarrow \\left[ \\begin{aligned} & 3y=-2z \\\\ & 3y=2z \\\\ \\end{aligned} \\right. \\\\ \\end{aligned}$ <span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A.<\/span>","column":2}]}],"id_ques":535},{"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/bai6/lv1/img\/8.jpg' \/><\/center> Bi\u1ec3u th\u1ee9c $y^2-4yz-3y+12z$ c\u00f3 m\u1ed9t nh\u00e2n t\u1eed l\u00e0 $y+3$. \u0110\u00fang hay sai?","select":["\u0110\u00fang","Sai"],"hint":"Ph\u00e2n t\u00edch bi\u1ec3u th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed theo ph\u01b0\u01a1ng ph\u00e1p nh\u00f3m h\u1ea1ng t\u1eed.","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> Nh\u00f3m $y^2-4yz-3y+12z=(y^2-4yz)-(3y-12z)$<br\/> <b> B\u01b0\u1edbc 2: <\/b> Ph\u00e2n t\u00edch bi\u1ec3u 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 3:<\/b> N\u1ebfu k\u1ebft qu\u1ea3 ph\u00e2n t\u00edch c\u00f3 ch\u1ee9a nh\u00e2n t\u1eed $y+3$ th\u00ec \u0111\u00e1p \u00e1n l\u00e0 \u0111\u00fang v\u00e0 ng\u01b0\u1ee3c l\u1ea1i. <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3: <br\/>$\\begin{align} & {{y}^{2}}-4yz-3y+12z \\\\ & =({{y}^{2}}-4yz)-(3y-12z) \\\\ & =y\\left( y-4z \\right)-3\\left( y-4z \\right) \\\\ & =\\left( y-4z \\right)\\left( y-3 \\right) \\\\ \\end{align}$ <br\/> Bi\u1ec3u th\u1ee9c kh\u00f4ng ch\u1ee9a nh\u00e2n t\u1eed $y+3$ .<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 Sai.<\/span>","column":2}]}],"id_ques":536},{"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/bai6/lv1/img\/8.jpg' \/><\/center> Bi\u1ec3u th\u1ee9c $35x^2-15xy+7x-3y$ c\u00f3 m\u1ed9t nh\u00e2n t\u1eed l\u00e0 $5x+1$. \u0110\u00fang hay sai?","select":["\u0110\u00fang","Sai"],"hint":"Ph\u00e2n t\u00edch bi\u1ec3u th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed theo ph\u01b0\u01a1ng ph\u00e1p nh\u00f3m h\u1ea1ng t\u1eed.","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> B\u01b0\u1edbc 1: <\/b> Nh\u00f3m $35x^2-15xy+7x-3y=(35x^2-15xy)+(7x-3y)$<br\/> <b> B\u01b0\u1edbc 2: <\/b> Ph\u00e2n t\u00edch bi\u1ec3u 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 3:<\/b> N\u1ebfu k\u1ebft qu\u1ea3 ph\u00e2n t\u00edch c\u00f3 ch\u1ee9a nh\u00e2n t\u1eed $5x+1$ th\u00ec \u0111\u00e1p \u00e1n l\u00e0 \u0111\u00fang v\u00e0 ng\u01b0\u1ee3c l\u1ea1i. <br\/> <span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3: <br\/>$\\begin{align} & 35{{x}^{2}}-15xy+7x-3y \\\\ & =(35{{x}^{2}}-15xy)+(7x-3y) \\\\ & =5x\\left( 7x-3y \\right)+\\left( 7x-3y \\right) \\\\ & =\\left( 7x-3y \\right)\\left( 5x+1 \\right) \\\\ \\end{align}$ <br\/> Bi\u1ec3u th\u1ee9c c\u00f3 ch\u1ee9a nh\u00e2n t\u1eed $5x+1$ .<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 \u0110\u00fang.<\/span>","column":2}]}],"id_ques":537},{"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/bai6/lv1/img\/13.jpg' \/><\/center> Bi\u1ec3u th\u1ee9c $x^3-6x^2+12x-8$ l\u00e0 l\u1eadp ph\u01b0\u01a1ng c\u1ee7a m\u1ed9t hi\u1ec7u. \u0110\u00fang hay sai? ","select":["\u0110\u00fang","Sai"],"hint":"","explain":"<span class='basic_left'> Ta c\u00f3: <br\/>$x^3-6x^2+12x-8=(x-2)^3$<br\/> Bi\u1ec3u th\u1ee9c l\u00e0 l\u1eadp ph\u01b0\u01a1ng c\u1ee7a m\u1ed9t hi\u1ec7u.<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 \u0110\u00fang.<\/span>","column":2}]}],"id_ques":538},{"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/bai6/lv1/img\/12.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed r\u1ed3i t\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c $a^5-a^3+a^2-1$ t\u1ea1i $a = 1$. <br\/> \u0110\u00e1p \u00e1n l\u00e0: _input_","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 $a^5-a^3+a^2-1$$=(a^5-a^3)+(a^2-1)$<br\/> <b>B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch bi\u1ec3u th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed theo ph\u01b0\u01a1ng ph\u00e1p \u0111\u1eb7t nh\u00e2n t\u1eed chung $(a+1)^2(a-1)(a^2-a+1)$.<br\/> <b>B\u01b0\u1edbc 3:<\/b> Thay $a = 1$ v\u00e0o bi\u1ec3u 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>: <br\/> $\\begin{align} & {{a}^{5}}-{{a}^{3}}+{{a}^{2}}-1 \\\\ & =({{a}^{5}}-{{a}^{3}})+({{a}^{2}}-1) \\\\ & ={{a}^{3}}\\left( {{a}^{2}}-1 \\right)+\\left( {{a}^{2}}-1 \\right) \\\\ & =\\left( {{a}^{2}}-1 \\right)\\left( {{a}^{3}}+1 \\right) \\\\ & =\\left( a+1 \\right)\\left( a-1 \\right)\\left( a+1 \\right)\\left( {{a}^{2}}-a+1 \\right) \\\\ & ={{\\left( a+1 \\right)}^{2}}\\left( a-1 \\right)\\left( {{a}^{2}}-a+1 \\right) \\\\ \\end{align}$ <br\/>Thay $a = 1$ v\u00e0o bi\u1ec3u th\u1ee9c \u0111\u00e3 thu g\u1ecdn, ta \u0111\u01b0\u1ee3c:<br\/> $(1+1)^2(1-1)(1^2-1+1)=0$ . <br\/> <b> C\u00e1ch 2: <\/b> Thay $a = 1$ v\u00e0o bi\u1ec3u th\u1ee9c $a^5-a^3+a^2-1$, ta \u0111\u01b0\u1ee3c: <br\/> $1^5 - 1^3 + 1^2 - 1 = 1 - 1 + 1 - 1 = 0$ <br\/> <span class='basic_pink'> Do \u0111\u00f3 s\u1ed1 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $0$. <\/span><\/span> "}]}],"id_ques":539},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["108"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/11.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed r\u1ed3i t\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c $18y^3-18y$ t\u1ea1i $y = 2$. <br\/> \u0110\u00e1p \u00e1n l\u00e0: _input_","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 bi\u1ec3u 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> Thay $y = 2$ v\u00e0o bi\u1ec3u 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> <br\/>Ta c\u00f3: <br\/> $18y^3-18y=18y(y^2-1)=18y(y+1)(y-1)$ <br\/>Thay $y = 2$ v\u00e0o bi\u1ec3u th\u1ee9c ta \u0111\u01b0\u1ee3c:<br\/> $18.2.(2+1)(2-1) =36.3.1=108$ <br\/> <b> C\u00e1ch 2: <\/b> Thay $y = 2$ v\u00e0o bi\u1ec3u th\u1ee9c $18y^3-18y$, ta \u0111\u01b0\u1ee3c: <br\/> $18 . 2^3 - 18 . 2 = 144 - 36 = 108$ <br\/> <span class='basic_pink'> Do \u0111\u00f3 s\u1ed1 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $108$. <\/span><\/span> "}]}],"id_ques":540},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["198"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/5.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed r\u1ed3i t\u00ednh gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c $x(y-1)-y(y-1)$ t\u1ea1i $x = 200; y = 2$. <br\/> \u0110\u00e1p \u00e1n l\u00e0: _input_","hint":"Ph\u00e2n t\u00edch bi\u1ec3u th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed theo ph\u01b0\u01a1ng ph\u00e1p \u0111\u1eb7t nh\u00e2n t\u1eed chung .<br\/> Thay $x = 200; y = 2$ v\u00e0o bi\u1ec3u th\u1ee9c \u0111\u1ec3 t\u00ednh gi\u00e1 tr\u1ecb.","explain":"<span class='basic_left'> Ta c\u00f3: <br\/> $x(y-1)-y(y-1)$$=\\left( y-1 \\right)\\left( x-y \\right)$ <br\/>Thay $x = 200; y = 2$ v\u00e0o bi\u1ec3u th\u1ee9c ta \u0111\u01b0\u1ee3c:<br\/>$\\left( 2-1 \\right)\\left( 200-2 \\right)=1.198=198$ . <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $198$. <\/span><\/span> "}]}],"id_ques":541},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank_random","correct":[[["-7"],["4"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/16.jpg' \/><\/center> Bi\u1ebft $x(x+7)=4x+28$, 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":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> B\u01b0\u1edbc 1:<\/b> Chuy\u1ec3n v\u1ec1 c\u00f9ng m\u1ed9t v\u1ebf $x(x+7)-(4x+28)=0$ <br\/> <b>B\u01b0\u1edbc 2:<\/b> V\u1ebf tr\u00e1i: Ph\u00e2n t\u00edch th\u00e0nh nh\u00e2n t\u1eed theo ph\u01b0\u01a1ng ph\u00e1p \u0111\u1eb7t nh\u00e2n t\u1eed chung $(x+7)(x-4)$.<br\/> <b> B\u01b0\u1edbc 3:<\/b> N\u1ebfu $a.b = 0$ th\u00ec $a = 0$ ho\u1eb7c $b = 0$. <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3:<br\/> $ x(x+7)=4x+28 \\\\ \\Leftrightarrow x\\left( x+7 \\right)-\\left( 4x+28 \\right)=0 \\\\ \\Leftrightarrow x\\left( x+7 \\right)-4\\left( x+7 \\right)=0 \\\\ \\Leftrightarrow \\left( x+7 \\right)\\left( x-4 \\right)=0 \\\\ \\Leftrightarrow \\left[ \\begin{aligned} & x+7=0 \\\\ & x-4=0 \\\\ \\end{aligned} \\right.\\Leftrightarrow \\left[ \\begin{aligned} & x=-7 \\\\ & x=4 \\\\ \\end{aligned} \\right. $ <br\/> <span class='basic_pink'> Do \u0111\u00f3 c\u00e1c s\u1ed1 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $4$ v\u00e0 $-7$. <\/span><\/span> "}]}],"id_ques":542},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank_random","correct":[[["-2"],["-1"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/3.jpg' \/><\/center> Bi\u1ebft $(x+2)^2=x+2$, 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":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b> B\u01b0\u1edbc 1:<\/b> Chuy\u1ec3n v\u1ec1 c\u00f9ng m\u1ed9t v\u1ebf $(x+2)^2-(x+2)=0$ <br\/> <b>B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch v\u1ebf tr\u00e1i th\u00e0nh nh\u00e2n t\u1eed theo ph\u01b0\u01a1ng ph\u00e1p \u0111\u1eb7t nh\u00e2n t\u1eed chung $(x+2)(x+1)$.<br\/> <b> B\u01b0\u1edbc 3:<\/b> N\u1ebfu $a.b = 0$ th\u00ec $a = 0$ ho\u1eb7c $b = 0$. <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3:<br\/> $ {{(x+2)}^{2}}=x+2 \\\\ \\Leftrightarrow {{\\left( x+2 \\right)}^{2}}-\\left( x+2 \\right)=0 \\\\ \\Leftrightarrow \\left( x+2 \\right)\\left[ \\left( x+2 \\right)-1 \\right]=0 \\\\ \\Leftrightarrow \\left( x+2 \\right)\\left( x+1 \\right)=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. $ <br\/> <span class='basic_pink'> Do \u0111\u00f3 c\u00e1c s\u1ed1 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $-2$ v\u00e0 $-1$. <\/span><\/span> "}]}],"id_ques":543},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank_random","correct":[[["0"],["1"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/3.jpg' \/><\/center> Bi\u1ebft $x(x-1)=0$, 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":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> N\u1ebfu $a.b = 0$ th\u00ec $a = 0$ ho\u1eb7c $b = 0$. <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/> Ta c\u00f3:<br\/> $ 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. $ <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $0$ v\u00e0 $1$. <\/span><\/span> "}]}],"id_ques":544},{"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":[[["2y","2y+z","z+2y"],["2y+z","2y","z+2y"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/8.jpg' \/><\/center> $2yz^2-8y^3$$=(\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})\\times (z-2y)\\times (\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})$ ","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/><b> B\u01b0\u1edbc 1:<\/b> \u0110\u1eb7t $2y$ l\u00e0 nh\u00e2n t\u1eed chung: $2y(z^2-4y^2)$<br\/> <b> B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch $(z^2-4y^2)$ theo ph\u01b0\u01a1ng ph\u00e1p d\u00f9ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c: $a^2-b^2=(a+b)(a-b)$, coi $a = z; b = 2y$ <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $\\begin{align} 2y{{z}^{2}}-8{{y}^{3}}&=2y({{z}^{2}}-4{{y}^{2}}) \\\\ & =2y\\left[ {{z}^{2}}-{{\\left( 2y \\right)}^{2}} \\right] \\\\ & =2y\\left[ \\left( z+2y \\right)\\left( z-2y \\right) \\right] \\\\ & =2y\\left( z+2y \\right)\\left( z-2y \\right) \\\\ \\end{align}$ <span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n c\u1ea7n \u0111i\u1ec1n l\u00e0 $2y$ v\u00e0 $z + 2y$.<\/span>"}]}],"id_ques":545},{"time":24,"part":[{"title":"\u0110i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng trong k\u1ebft qu\u1ea3 ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed","title_trans":"","temp":"fill_the_blank_random","correct":[[["27z"],["y+z","z+y"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/10.jpg' \/><\/center> $27z^3-27y^2z$$=(\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})\\times (z-y)\\times (\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})$ ","hint":" \u0110\u1eb7t 27z l\u00e0 nh\u00e2n t\u1eed chung: $27z(z^2-y^2)$ <br\/>Sau \u0111\u00f3 ph\u00e2n t\u00edch $(z^2-y^2)$ theo ph\u01b0\u01a1ng ph\u00e1p d\u00f9ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c: $a^2-b^2=(a+b)(a-b)$, coi $a = z; b = y$ ","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/><b> B\u01b0\u1edbc 1:<\/b> \u0110\u1eb7t 27z l\u00e0 nh\u00e2n t\u1eed chung: $27z(z^2-y^2)$<br\/> <b> B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch $(z^2-y^2)$ theo ph\u01b0\u01a1ng ph\u00e1p d\u00f9ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c: $a^2-b^2=(a+b)(a-b)$, coi $a = z; b = y$ <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $27z^3-27y^2z=27z(z^2-y^2)$$=27z(z+y)(z-y)$.<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n c\u1ea7n \u0111i\u1ec1n l\u00e0 $27z$ v\u00e0 $y + z$.<\/span>"}]}],"id_ques":546},{"time":24,"part":[{"title":"\u0110i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng trong k\u1ebft qu\u1ea3 ph\u00e2n t\u00edch \u0111a th\u1ee9c th\u00e0nh nh\u00e2n t\u1eed","title_trans":"","temp":"fill_the_blank_random","correct":[[["2z"],["1+z","z+1"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/8.jpg' \/><\/center> $2z-2z^3$$=(\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})\\times (1-z)\\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> \u0110\u1eb7t $2z$ l\u00e0 nh\u00e2n t\u1eed chung: $2z(1-z^2)$<br\/> <b> B\u01b0\u1edbc 2:<\/b> Ph\u00e2n t\u00edch $(1-z^2)$ theo ph\u01b0\u01a1ng ph\u00e1p d\u00f9ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c: $a^2-b^2=(a+b)(a-b)$, coi $a = 1; b = z$ <br\/><span class='basic_green'>V\u00e0i gi\u1ea3i:<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $2z-2z^3=2z(1-z^2)=2z(1-z)(1+z)$.<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n c\u1ea7n \u0111i\u1ec1n l\u00e0 $2z$ v\u00e0 $z + 1$.<\/span>"}]}],"id_ques":547},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/11.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c $(2x-1)^2-(x+3)^2$ th\u00e0nh nh\u00e2n t\u1eed, ta \u0111\u01b0\u1ee3c:","select":["A. $(x-2)(3x+4)$ ","B. $(x-4)(3x+2)$ ","C. $(3x-4)(3x+2)$","D. $(3x-2)(3x+3)$"],"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Ph\u00e2n t\u00edch theo ph\u01b0\u01a1ng ph\u00e1p d\u00f9ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c: $a^2-b^2=(a+b)(a-b)$, coi $a = 2x-1; b = x+3$ <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/>Ta c\u00f3:<br\/> $(2x-1)^2-(x+3)^2$$=[(2x-1)+(x+3)][(2x-1)-(x+3)]$$=(3x+2)(x-4)$.<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B.<\/span>","column":2}]}],"id_ques":548},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/9.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c $1-8x^3$ th\u00e0nh nh\u00e2n t\u1eed, ta \u0111\u01b0\u1ee3c:","select":["A. $(1-2x)(1+2x)$ ","B. $(1-4x)(1+4x+16x^2)$ ","C. $(1-2x)(1+2x+4x^2)$","D. $(1-2x)(1-2x+4x^2)$"],"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Ph\u00e2n t\u00edch theo ph\u01b0\u01a1ng ph\u00e1p d\u00f9ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c: $a^3-b^3=(a-b)(a^2+ab+b^2)$ <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $1-8x^3=1^3-(2x)^3=(1-2x)(1+2x+4x^2)$.<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span>","column":2}]}],"id_ques":549},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai6/lv1/img\/8.jpg' \/><\/center> Ph\u00e2n t\u00edch \u0111a th\u1ee9c $x^2-x$ th\u00e0nh nh\u00e2n t\u1eed, ta \u0111\u01b0\u1ee3c:","select":["A. $x(x^2-1)$ ","B. $x(x-1)$ ","C. $x.x-1$","D. $x^2(x-1)$"],"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Ph\u00e2n t\u00edch theo ph\u01b0\u01a1ng ph\u00e1p \u0111\u1eb7t nh\u00e2n t\u1eed chung.<br\/> Nh\u00e2n t\u1eed chung l\u00e0 $x$. <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i:<\/span><br\/><span class='basic_left'>Ta c\u00f3:<br\/> $x^2-x=x.x-x=x(x-1)$.<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B.<\/span>","column":2}]}],"id_ques":550}],"lesson":{"save":0,"level":1}}