Phân tích đa thức thành nhân tử :
a) (x^2+xy)^2 -(y^2+xy)^2
b) -x^2+2xy-y^2+1
c) x^2y+xy^2-x-y
d) ax^2-ay^2-7x+7y
e) x^4-x^3-x+1
g) 27x^3+27x^2+9x+1+x+1/3
h) x(x+1)^2+x(x-5)-5(x+1)^2
i) ax^2+bx^2-bx-ax+cx^2-cx
k) 7x^2y^2-63x^2
m) 81-(x^2+6x)^2
n) 36-4a^2+20ab-25b^2
p) x^2+2xy+y^2-xz-yz
q) a^3+3a^2+3a+1-27b^3
Làm được câu nào thì làm nka :))
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3 câu trả lời 387
`a)`
`(x^2+xy)^2-(y^2+xy)^2`
`=(x^2+xy-y^2-xy)(x^2+xy+y^2+xy)`
`=(x^2-y^2)(x^2+2xy+y^2)`
`=(x-y)(x+y)(x+y)^2`
`=(x-y)(x+y)^3`
`b)`
`-x^2+2xy-y^2+1`
`=-(x^2-2xy+y^2-1)`
`=-[(x-y)^2-1]`
`=-(x-y-1)(x-y+1)`
`c)`
`x^2y+xy^2-x-y`
`=(x^2y-x)+(xy^2-y)`
`=x(xy-1)+y(xy-1)`
`=(xy-1)(x+y)`
`d)`
`ax^2-ay^2-7x+7y`
`=(ax^2-ay^2)-(7x-7y)`
`=a(x^2-y^2)-7(x-y)`
`=a[(x-y)(x+y)]-7(x-y)`
`=(x-y)(ax+ay-7)`
`e)`
`x^4-x^3-x+1`
`=(x^4-x^3)-(x-1)`
`=x^3(x-1)-(x-1)`
`=(x-1)(x^3-1)`
`=(x-1)(x-1)(x^2+x.1+1^2)`
`=(x-1)^2(x^2+x+1)`
`g)`
`27x^3+27x^2+9x+1+x+1/3`
`=(27x^3+27x^2+9x+1)+(x+1/3)`
`=(3x+1)^3+1/3(3x+1)`
`=(3x+1)[(3x+1)^2+1/3]`
`=(3x+1)(9x^2+6x+1+1/3)`
`=(3x+1)(9x^2+6x+4/3)`
`h)`
`x(x+1)^2+x(x-5)-5(x+1)^2`
`=[x(x+1)^2-5(x+1)^2]+x(x-5)`
`=(x+1)^2(x-5)+x(x-5)`
`=(x-5)[(x+1)^2+x]`
`=(x-5)(x^2+2x+1+x)`
`=(X-5)(x^2+3x+1)`
`i)`
`ax^2+bx^2-bx-ax+cx^2-cx`
`=(ax^2-ax)+(bx^2-bx)+(cx^2-cx)`
`=ax(x-1)+bx(x-1)+cx(x-1)`
`=(x-1)(ax+bx+cx)`
`=x(x-1)(a+b+c)`
`k)`
`7x^2y^2-63x^2`
`=7x^2(y^2-9)`
`=7x^2(y-3)(y+3)`
`k)`
`7x^2y^2-63x^2`
`=7x^2(y^2-9)`
`=7x^2(y-3)(y+3)`
`m)`
`81-(x^2+6x)^2`
`=[9-(x^2+6x)][9+(x^2+6x)]`
`=(9-x^2-6x)(9+x^2+6x)`
`n)`
`36-4a^2+20ab-25b^2`
`=36-(4a^2-20ab+25b^2)`
`=6^2-(2a-5b)^2`
`=[6-(2a-5b)][6+(2a-5b)]`
`=(6-2a+5b)(6+2a-5b)`
`p)`
`x^2+2xy+y^2-xz-yz`
`=(x^2+2xy+y^2)-(xz+yz)`
`=(x+y)^2-z(x+y)`
`=(x+y)(x+y-z)`
`q)`
`a^3+3a^2+3a+1-27b^3`
`=(a^3+3a^2+3a+1)-27b^3`
`=(a+1)^3-(3b)^3`
`=(a+1-3b)[(a+1)^2+(a+1).3b+(3b)^2]`
`=(a-3b+1)(a^2+2a+1+3ab+3b+9b^2)`
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