{"segment":[{"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":[["2","3","1"]],"list":[{"point":5,"image":"https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/2.jpg","left":["$a^2-b^2$","$(a+b)^3$","$a^3+b^3$"],"right":["$(a+b)(a^2-ab+b^2)$","$(a+b)(a-b)$","$a^3+3a^2b+3ab^2+b^3$"],"top":100,"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Ta khai tri\u1ec3n bi\u1ec3u th\u1ee9c \u1edf v\u1ebf tr\u00e1i theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c. 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: <br\/>$a^2-b^2=(a+b)(a-b)$<br\/> $(a+b)^3=a^3+3a^2b+3ab^2+b^3$<br\/> $a^3+b^3=(a+b)(a^2-ab+b^2)$ <br\/> <span class='basic_pink'>K\u1ebft lu\u1eadn:<br\/> N\u1ed1i $1$ v\u1edbi $(a+b)(a-b)$<br\/> N\u1ed1i $2$ v\u1edbi $a^3+3a^2b+3ab^2+b^3$<br\/> N\u1ed1i $3$ v\u1edbi $(a+b)(a^2-ab+b^2)$.<\/span> <\/span>"}]}],"id_ques":481},{"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":[["3","1","2"]],"list":[{"point":5,"image":"https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/1.png","left":["$(2-y)(y^2+2y+4)$","$(2-y)(2+y)$","$8-12y+6y^2-y^3$"],"right":["$4-y^2$","$(2-y)^3$","$8-y^3$"],"top":100,"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Ta r\u00fat g\u1ecdn c\u00e1c bi\u1ec3u th\u1ee9c \u1edf c\u1ed9t tr\u00e1i theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c \u0111\u00e3 h\u1ecdc. 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: $(2-y)(y^2+2y+4)=2^3-y^3$$=8-y^3$<br\/> $(2-y)(2+y)=4-y^2$<br\/> $8-12y+6y^2-y^3=(2-y)^3$ <br\/> <span class='basic_pink'>K\u1ebft lu\u1eadn:<br\/> N\u1ed1i $1$ v\u1edbi $8-y^3$<br\/> N\u1ed1i $2$ v\u1edbi $4-y^2$<br\/> N\u1ed1i $3$ v\u1edbi $(2-y)^3$.<\/span> <\/span>"}]}],"id_ques":482},{"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/bai5/lv1/img\/5.jpg' \/><\/center> Vi\u1ebft $64-x^3=(32-x)(32+x)$ l\u00e0 <b> \u0111\u00fang <\/b> hay <b> sai <\/b>? ","select":["\u0110\u00fang","Sai"],"hint":"","explain":" <span class='basic_left'>Ta c\u00f3: <br\/> V\u1ebf ph\u1ea3i $=32^2-x^2=1024-x^2$ <br\/> V\u1ebf tr\u00e1i $=64-x^3$ <br\/>Do v\u1eady, v\u1ebf tr\u00e1i kh\u00e1c v\u1ebf ph\u1ea3i n\u00ean kh\u1eb3ng \u0111\u1ecbnh tr\u00ean l\u00e0 sai<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 Sai.<\/span>","column":2}]}],"id_ques":483},{"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/bai5/lv1/img\/5.jpg' \/><\/center>Bi\u1ec3u th\u1ee9c $A=(a^2-2)(a^4+a^2+4)$ l\u00e0 hi\u1ec7u hai l\u1eadp ph\u01b0\u01a1ng. <b> \u0110\u00fang <\/b> hay <b> Sai <\/b>? ","select":["\u0110\u00fang","Sai"],"hint":" ","explain":"<span class='basic_left'>Ta c\u00f3: $A=(a^2-2)(a^4+a^2+4)$ kh\u00f4ng l\u00e0 hi\u1ec7u hai l\u1eadp ph\u01b0\u01a1ng v\u00ec $a^4+a^2+4$ thi\u1ebfu h\u1ec7 s\u1ed1 2 \u1edf $a^2$.<br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0: Sai.<\/span>","column":2}]}],"id_ques":484},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["-5"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/4.jpg' \/><\/center>Bi\u1ebft $(x+2)^3+27=0$, gi\u00e1 tr\u1ecb c\u1ee7a $x$ l\u00e0 _input_","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b>C\u00e1ch 1:<\/b> Ta c\u00f3 $27=3^3$, \u0111\u01b0a v\u1ec1 d\u1ea1ng $a^3=b^3$ th\u00ec $a = b$.<br\/> <b>C\u00e1ch 2:<\/b> Khai tri\u1ec3n v\u1ebf tr\u00e1i $(x+2)^3+27$ theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c t\u1ed5ng hai l\u1eadp ph\u01b0\u01a1ng. <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\/><b>C\u00e1ch 1<\/b><br\/> Ta c\u00f3:<br\/>$ {{\\left( x+2 \\right)}^{3}}+27=0 \\\\ \\Leftrightarrow {{\\left( x+2 \\right)}^{3}}=-27 \\\\ \\Leftrightarrow {{\\left( x+2 \\right)}^{3}}={({-3})^{3}} \\\\ \\Leftrightarrow x+2=-3 \\\\ \\Leftrightarrow x=-5 $<br\/><b>C\u00e1ch 2<\/b> <br\/> Ta c\u00f3:<br\/> ${{\\left( x+2 \\right)}^{3}}+27=0 \\\\ \\Leftrightarrow {{\\left( x+2 \\right)}^{3}}+{{3}^{3}}=0 \\\\ \\Leftrightarrow \\left( x+2+3 \\right)\\left[ {{\\left( x+2 \\right)}^{2}}-3\\left( x+2 \\right)+{{3}^{2}} \\right] =0 \\\\ \\Leftrightarrow \\left( x+5 \\right)\\left( {{x}^{2}}+4x+4-3x-6+9 \\right) =0 \\\\ \\Leftrightarrow \\left( x+5 \\right)\\left( {{x}^{2}}+x+7 \\right) =0 $<br\/>$ \\text{Do} \\,\\,{{x}^{2}}+x+7 = \\left( x + \\dfrac{1}{2} \\right)^2 + \\dfrac{27}{4} >0 \\Rightarrow x+5=0\\Rightarrow x=-5 $ <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $-5$. <\/span><\/span> "}]}],"id_ques":485},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["3"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/4.jpg' \/><\/center>Bi\u1ebft $(x-1)^3-8=0$, gi\u00e1 tr\u1ecb c\u1ee7a $x$ l\u00e0 _input_","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/> <b>C\u00e1ch 1<\/b>: Ta c\u00f3 $8=2^3$, \u0111\u01b0a v\u1ec1 d\u1ea1ng $a^3=b^3$ th\u00ec $a = b$.<br\/><b>C\u00e1ch 2<\/b>: Khai tri\u1ec3n v\u1ebf tr\u00e1i $(x-1)^3-8$ theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c hi\u1ec7u hai l\u1eadp ph\u01b0\u01a1ng. <br\/> 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\/><b>C\u00e1ch 1<\/b><br\/> Ta c\u00f3:<br\/>$ {{\\left( x-1 \\right)}^{3}}-8=0 \\\\ \\Leftrightarrow {{\\left( x-1 \\right)}^{3}}=8 \\\\ \\Leftrightarrow {{\\left( x-1 \\right)}^{3}}={{2}^{3}} \\\\ \\Leftrightarrow x-1=2 \\\\ \\Leftrightarrow x=3 $ <br\/><b>C\u00e1ch 2<\/b> <br\/> Ta c\u00f3:<br\/> $ {{\\left( x-1 \\right)}^{3}}-8=0 \\\\ \\Leftrightarrow {{\\left( x-1 \\right)}^{3}}-{{2}^{3}}=0 \\\\ \\Leftrightarrow \\left( x-1-2 \\right)\\left[ {{\\left( x-1 \\right)}^{2}}+2\\left( x-1 \\right)+{{2}^{2}} \\right] =0 \\\\ \\Leftrightarrow \\left( x-3 \\right)\\left( {{x}^{2}}-2x+1+2x-2+4 \\right) =0 \\\\ \\Leftrightarrow \\left( x-3 \\right)\\left( {{x}^{2}}+3 \\right) =0 (*) $<br\/>$ \\text{Do}\\,\\,\\,{{x}^{2}}+3\\geq 3 (\\forall x)$ <br\/> $\\Rightarrow (*) = 0 \\Leftrightarrow x-3=0\\Rightarrow x=3 $ <br\/> <span class='basic_pink'> Do \u0111\u00f3 s\u1ed1 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $3$. <\/span><\/span> "}]}],"id_ques":486},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["224"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/4.jpg' \/><\/center> Gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c $(2-3y)(4+6y+9y^2)$ v\u1edbi $y = -2$ 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> R\u00fat g\u1ecdn bi\u1ec3u th\u1ee9c <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\/> Ta c\u00f3: <br\/> $(2-3y)(4+6y+9y^2)=2^3-(3y)^3$$=8-27y^3$ <br\/> Thay $y = -2$ v\u00e0o bi\u1ec3u th\u1ee9c sau khi r\u00fat g\u1ecdn, ta \u0111\u01b0\u1ee3c: <br\/> $8-27.(-2)^3=8+216=224$ . <br\/> <span class='basic_pink'> Do \u0111\u00f3 s\u1ed1 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $224$. <\/span><\/span> "}]}],"id_ques":487},{"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":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/5.jpg' \/><\/center> Gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c $(a-b)(a^2+ab+b^2)$ v\u1edbi $a = 2; b = -1$ 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> R\u00fat g\u1ecdn bi\u1ec3u th\u1ee9c .<br\/> <b>B\u01b0\u1edbc 2:<\/b> Thay $a = 2; b = -1$ 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\/> Ta c\u00f3: <br\/> $(a-b)(a^2+ab+b^2)=a^3-b^3$ <br\/> Thay $a = 2; b = -1$ v\u00e0o bi\u1ec3u th\u1ee9c sau khi r\u00fat g\u1ecdn, ta \u0111\u01b0\u1ee3c: <br\/> $2^3-(-1)^3=8-(-1)=8+1=9$ . <br\/> <span class='basic_pink'> Do \u0111\u00f3 s\u1ed1 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u00e0 $9$. <\/span><\/span> "}]}],"id_ques":488},{"time":24,"part":[{"title":"\u0110i\u1ec1n k\u1ebft qu\u1ea3 v\u00e0o \u00f4 tr\u1ed1ng ","title_trans":"","temp":"fill_the_blank","correct":[[["-26"],["27"]]],"list":[{"point":5,"width":40,"type_input":"","input_hint":["frac","sqr"],"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/5.jpg' \/><\/center> Gi\u00e1 tr\u1ecb c\u1ee7a bi\u1ec3u th\u1ee9c $\\left( \\dfrac{1}{3}+a \\right)\\left( \\dfrac{1}{9}-\\dfrac{1}{3}a+{{a}^{2}} \\right)$ v\u1edbi $a = - 1$ l\u00e0 <div class=\"frac123\"><div class=\"ts\">_input_<\/div><div class=\"ms\">_input_<\/div><\/div>","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/><b>B\u01b0\u1edbc 1:<\/b> R\u00fat g\u1ecdn bi\u1ec3u th\u1ee9c .<br\/><b>B\u01b0\u1edbc 2:<\/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\/> Ta c\u00f3: <br\/> $\\left( \\dfrac{1}{3}+a \\right)\\left( \\dfrac{1}{9}-\\dfrac{1}{3}a+{{a}^{2}} \\right) \\\\ ={{\\left( \\dfrac{1}{3} \\right)}^{3}}+{{a}^{3}} \\\\ =\\dfrac{1}{27}+{{a}^{3}}$ <br\/> Thay $a = -1$ v\u00e0o bi\u1ec3u th\u1ee9c sau khi thu g\u1ecdn, ta \u0111\u01b0\u1ee3c: <br\/> $\\dfrac{1}{27}+{{\\left( -1 \\right)}^{3}}=\\dfrac{1}{27}-1=\\dfrac{-26}{27}$ .<\/span> "}]}],"id_ques":489},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t<br\/> \u0110\u01b0a v\u1ec1 d\u1ea1ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c $a^3-b^3$ ho\u1eb7c $a^3+b^3$","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/3.jpg' \/><\/center>$(y-x)(x^2+xy+y^2) = ?$","select":["A. $x^3-y^3$ ","B. $x^3-y^2$ ","C. $y^3-x^3$","D. $x^3+y^3$"],"hint":"S\u1eed d\u1ee5ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c: $a^3-b^3$ v\u1edbi $a = y, b = x$.","explain":"<span class='basic_left'>Ta c\u00f3: <br\/> $(y-x)(x^2+xy+y^2)$$=y^3-x^3.$<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span>","column":2}]}],"id_ques":490},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t<br\/> \u0110\u01b0a v\u1ec1 d\u1ea1ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c $a^3-b^3$ ho\u1eb7c $a^3+b^3$","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/3.jpg' \/><\/center>$(x^2-2x+4)(x+2) = ?$","select":["A. $x^3+8$ ","B. $x^3-8$ ","C. $x^2-4$","D. $(x+2)^3$"],"hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn<\/span><br\/> <b>B\u01b0\u1edbc 1:<\/b> S\u1eed d\u1ee5ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c $a^3+b^3$<br\/><b>B\u01b0\u1edbc 2:<\/b> T\u00ecm \u0111\u01b0\u1ee3c $a = x, b = 2$ .<br\/><span class='basic_green'>Gi\u1ea3i<\/span><br\/><span class='basic_left'> Ta c\u00f3: <br\/> $(x^2-2x+4)(x+2)$$=x^3+2^3=x^3+8$ .<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 A.<\/span>","column":2}]}],"id_ques":491},{"time":24,"part":[{"title":"\u0110i\u1ec1n d\u1ea5u $+$ ho\u1eb7c $-$ v\u00e0o \u00f4 tr\u1ed1ng \u0111\u1ec3 \u0111\u01b0\u1ee3c m\u1ed9t khai tri\u1ec3n \u0111\u00fang ","title_trans":"","temp":"fill_the_blank","correct":[[["-"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/4.jpg' \/><\/center>$(1-a^2)(1+a^2+a^4)$$=1\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}a^6$ ","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Ta \u0111\u01b0a $(1-a^2)(1+a^2+a^4)$ v\u1ec1 hi\u1ec7u c\u1ee7a hai l\u1eadp ph\u01b0\u01a1ng: $a^3-b^3=(a-b)(a^2+ab+b^2)$, t\u1eeb \u0111\u00f3 t\u00ecm ra d\u1ea5u c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng.<br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/>Ta c\u00f3: <br\/>V\u1ebf tr\u00e1i$= (1-a^2)(1+a^2+a^4)=1-(a^2)^3=1-a^6$. <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng d\u1ea5u $-$. <\/span><\/span> "}]}],"id_ques":492},{"time":24,"part":[{"title":"\u0110i\u1ec1n d\u1ea5u $+$ ho\u1eb7c $-$ v\u00e0o \u00f4 tr\u1ed1ng \u0111\u1ec3 \u0111\u01b0\u1ee3c m\u1ed9t khai tri\u1ec3n \u0111\u00fang ","title_trans":"","temp":"fill_the_blank","correct":[[["-"],["+"],["+"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/5.jpg' \/><\/center>$125-b^3$$=(5\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}b)(25\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}5b\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}b^2)$ ","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Ta khai tri\u1ec3n $125-b^3$ theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c: $a^3-b^3$, t\u1eeb \u0111\u00f3 t\u00ecm ra c\u00e1c d\u1ea5u c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng.<br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/>Ta c\u00f3: <br\/>V\u1ebf tr\u00e1i $= 125-b^3=5^3-b^3$$=(5-b)(25+5b+b^2)$. <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u1ea7n l\u01b0\u1ee3t c\u00e1c d\u1ea5u $-$, $+$ v\u00e0 $+$. <\/span><\/span> "}]}],"id_ques":493},{"time":24,"part":[{"title":"\u0110i\u1ec1n d\u1ea5u $+$ ho\u1eb7c $-$ v\u00e0o \u00f4 tr\u1ed1ng \u0111\u1ec3 \u0111\u01b0\u1ee3c m\u1ed9t khai tri\u1ec3n \u0111\u00fang ","title_trans":"","temp":"fill_the_blank","correct":[[["+"],["-"],["+"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/5.jpg' \/><\/center>$8y^3+27z^3$$=(2y\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}3z)(4y^2\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}6yz\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}9z^2)$ ","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>Ta khai tri\u1ec3n $8y^3+27z^3$ theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c: $a^3+b^3=(a+b)(a^2-ab+b^2)$, t\u1eeb \u0111\u00f3 t\u00ecm ra c\u00e1c d\u1ea5u c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng.<br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/>Ta c\u00f3: <br\/>$VT = 8y^3+27z^3=(2y)^3+(3z)^3=(2y+3z)[(2y)^2-6yz+(3z)^2]$$=(2y+3z)(4y^2-6yz+9z^2)$ . <br\/> <span class='basic_pink'> Do \u0111\u00f3 ph\u1ea3i \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng l\u1ea7n l\u01b0\u1ee3t c\u00e1c d\u1ea5u +, - v\u00e0 +. <\/span><\/span> "}]}],"id_ques":494},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[1]],"list":[{"point":5,"select":["A. $a = 25; b=\\dfrac{5}{2}$","B. $a = 25; b = \\dfrac{5}{3}$","C. $a = 20; b=\\dfrac{5}{3}$"],"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/2.jpg' \/><\/center> ${{5}^{3}}-{{\\left( \\dfrac{1}{2}x \\right)}^{3}}$$=\\left( 5-\\dfrac{1}{2}x \\right)$($a$+b$x+\\dfrac{{{x}^{2}}}{4} )$. $a$ =?; b=? ","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>V\u1ebf tr\u00e1i l\u00e0 d\u1ea1ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c hi\u1ec7u hai l\u1eadp ph\u01b0\u01a1ng <br\/> Ta khai tri\u1ec3n \u0111\u1ec3 t\u00ecm c\u00e1c y\u1ebfu t\u1ed1 c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng. <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/>Ta c\u00f3: <br\/> ${{5}^{3}}-{{\\left( \\dfrac{1}{2}x \\right)}^{3}}$$=\\left( 5-\\dfrac{1}{2}x \\right)\\left( 25+\\dfrac{5}{2}x+\\dfrac{{{x}^{2}}}{4} \\right)$ .<\/span> "}]}],"id_ques":495},{"time":24,"part":[{"title":"Ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang","title_trans":"","temp":"multiple_choice","correct":[[3]],"list":[{"point":5,"select":["A. $x = a^3; y = 3a$","B. $x = a^2; y = 2a$","C. $x = a^2; y = 4a$"],"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/2.jpg' \/><\/center> $a^3-4^3=(a-4)(x+y+16)$. $x = ?; y =?$ ","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>V\u1ebf tr\u00e1i d\u1ea1ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c hi\u1ec7u hai l\u1eadp ph\u01b0\u01a1ng.<br\/> Ta khai tri\u1ec3n \u0111\u1ec3 t\u00ecm c\u00e1c y\u1ebfu t\u1ed1 c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng. <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/>Ta c\u00f3: <br\/> $a^3-4^3=(a-4)(a^2+4a+16)$ .<\/span> "}]}],"id_ques":496},{"time":24,"part":[{"title":"\u0110i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng \u0111\u1ec3 \u0111\u01b0\u1ee3c m\u1ed9t khai tri\u1ec3n \u0111\u00fang ","title_trans":"","temp":"fill_the_blank","correct":[[["2"],["y"]]],"list":[{"point":5,"width":40,"type_input":"","ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/2.jpg' \/><\/center>$2^3-y^3$$=(\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{}-\\FormInput[40][bl_elm_true basic_elm basic_blank basic_blank_part]{})(4+2y+y^2)$ ","hint":"","explain":"<span class='basic_left'><span class='basic_green'>H\u01b0\u1edbng d\u1eabn:<\/span><br\/>V\u1ebf tr\u00e1i l\u00e0 d\u1ea1ng h\u1eb1ng \u0111\u1eb3ng th\u1ee9c hi\u1ec7u hai l\u1eadp ph\u01b0\u01a1ng.<br\/> Ta khai tri\u1ec3n \u0111\u1ec3 t\u00ecm c\u00e1c y\u1ebfu t\u1ed1 c\u1ea7n \u0111i\u1ec1n v\u00e0o \u00f4 tr\u1ed1ng. <br\/><span class='basic_green'>B\u00e0i gi\u1ea3i<\/span><br\/>Ta c\u00f3: <br\/> $2^3-y^3=(2-y)(4+2y+y^2)$ .<br\/> <span class='basic_pink'>V\u1eady c\u1ea7n \u0111i\u1ec1n l\u00e0 $2$ v\u00e0 $y$. <\/span><\/span> "}]}],"id_ques":497},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[2]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/3.jpg' \/><\/center>Khai tri\u1ec3n $a^3+b^3$ theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c ta \u0111\u01b0\u1ee3c:","select":["A. $(a+b)(a^2+2ab+b^2)$ ","B. $(a+b)(a^2-ab+b^2)$ ","C. $(a+b)(a^2+2ab+b^2)$","D. $(a+b)(a^2-2ab+b^2)$"],"hint":"Khai tri\u1ec3n theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c:$a^3+b^3=(a+b)(a^2-ab+b^2)$.","explain":"<span class='basic_left'>Ta c\u00f3:<br\/> $a^3+b^3=(a+b)(a^2-ab+b^2)$.<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 B.<\/span>","column":2}]}],"id_ques":498},{"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/bai5/lv1/img\/3.jpg' \/><\/center>Khai tri\u1ec3n $1+x^6$ theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c ta \u0111\u01b0\u1ee3c:","select":["A. $(1-x^2)(1+x^2+x^4)$ ","B. $(1-x^3)(1-x^3+x^6)$ ","C. $(1+x^2)(1-x^2+x^4)$","D. $(1+x^3)(1-x^3+x^6)$"],"hint":"Khai tri\u1ec3n theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c:$a^3+b^3=(a+b)(a^2-ab+b^2)$.","explain":"<span class='basic_left'>Ta c\u00f3:<br\/> $1+{{x}^{6}}$$={{1}^{3}}+{{\\left( {{x}^{2}} \\right)}^{3}}$$=\\left( 1+{{x}^{2}} \\right)\\left( 1-{{x}^{2}}+{{x}^{4}} \\right)$.<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 C.<\/span>","column":2}]}],"id_ques":499},{"time":24,"part":[{"title":"L\u1ef1a ch\u1ecdn \u0111\u00e1p \u00e1n \u0111\u00fang nh\u1ea5t","title_trans":"","temp":"multiple_choice","correct":[[4]],"list":[{"point":5,"ques":"<center><img src='https://www.luyenthi123.com/file/luyenthi123/lop8/toan/daiso/bai5/lv1/img\/3.jpg' \/><\/center>Khai tri\u1ec3n ${{\\left( \\dfrac{1}{2} \\right)}^{3}}-{{x}^{3}}$ theo h\u1eb1ng \u0111\u1eb3ng th\u1ee9c ta \u0111\u01b0\u1ee3c:","select":["A. $\\left( \\dfrac{1}{2}-x \\right)\\left( \\dfrac{1}{8}+\\dfrac{1}{2}x+{{x}^{3}} \\right)$ ","B. $\\left( \\dfrac{1}{2}-x \\right)\\left( \\dfrac{1}{2}+x \\right)$ ","C. $\\left( \\dfrac{1}{2}-x \\right)\\left( \\dfrac{1}{4}-\\dfrac{1}{2}x+{{x}^{2}} \\right)$","D. $\\left( \\dfrac{1}{2}-x \\right)\\left( \\dfrac{1}{4}+\\dfrac{1}{2}x+{{x}^{2}} \\right)$"],"hint":"","explain":"<span class='basic_left'>Ta c\u00f3:<br\/> ${{\\left( \\dfrac{1}{2} \\right)}^{3}}-{{x}^{3}}$$=\\left( \\dfrac{1}{2}-x \\right)\\left( \\dfrac{1}{4}+\\dfrac{1}{2}x+{{x}^{2}} \\right)$.<span><br\/> <span class='basic_pink'> V\u1eady \u0111\u00e1p \u00e1n l\u00e0 D.<\/span>","column":2}]}],"id_ques":500}],"lesson":{"save":0,"level":1}}