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{"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}}

Điểm của bạn.

Câu hỏi này theo dạng chọn đáp án đúng, sau khi đọc xong câu hỏi, bạn bấm vào một trong số các đáp án mà chương trình đưa ra bên dưới, sau đó bấm vào nút gửi để kiểm tra đáp án và sẵn sàng chuyển sang câu hỏi kế tiếp

Trả lời đúng trong khoảng thời gian quy định bạn sẽ được + số điểm như sau:
Trong khoảng 1 phút đầu tiên + 5 điểm
Trong khoảng 1 phút -> 2 phút + 4 điểm
Trong khoảng 2 phút -> 3 phút + 3 điểm
Trong khoảng 3 phút -> 4 phút + 2 điểm
Trong khoảng 4 phút -> 5 phút + 1 điểm

Quá 5 phút: không được cộng điểm

Tổng thời gian làm mỗi câu (không giới hạn)

Điểm của bạn.

Bấm vào đây nếu phát hiện có lỗi hoặc muốn gửi góp ý