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因式分解【急】 y^2n+y^n+1/4 -1+16^4 1/4x^2+1/3xy-1/9y^2 a(a-b)^3+2a

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因式分解【急】 y^2n+y^n+1/4 -1+16^4 1/4x^2+1/3xy-1/9y^2 a(a-b)^3+2a^2(b-a)^2-2ab(b-a)^2
1.y^2n+y^n+1/4 2.-1+16a^4 3.1/4x^2+1/3xy-1/9y^2 4.a(a-b)^3+2a^2(b-a)^2-2ab(b-a)^2
因式分解【急】 y^2n+y^n+1/4 -1+16^4 1/4x^2+1/3xy-1/9y^2 a(a-b)^3+2a
1.y^2n+y^n+1/4
=(y^n)^2+y^n+1/4
=(y^n+1/2)^2
2.-1+16a^4
=16a^4-1
=(4a^2+1)(4a^2-1)
=(4a^2+1)(2n+1)(2n-1)
3.1/4x^2+1/3xy-1/9y^2
有没有写错?如果:
1/4x^2+1/3xy+1/9y^2
=(1/2x+1/3y)^2
如果没写错确实是1/4x^2+1/3xy-1/9y^2
= 1/4x^2+1/3xy+1/9y^2-2/9y^2
= (1/2x+1/3y)^2 - (根号2/3y)^2
=[1/2x+(1+根号2)/3 y] * [1/2x+(1-根号2)/3 y]
4.a(a-b)^3+2a^2(b-a)^2-2ab(b-a)^2
=a(a-b)^3+2a^2(a-b)^2-2ab(a-b)^2
=a(a-b)^2 {(a-b)+2a-2b}
=a(a-b)^2 (3a-3b)
=3a(a-b)^3