因式分解(x+y)^4+(x^2-y^2)^2-(x-y)^4
3个回答

确定最后一项是- 这样的话没法分解啊,我下面按照+分解,不明白欢迎追问!

利用换元法

设x+y=a,x-y=b,则

(x+y)^4+(x^2-y^2)^2+(x-y)^4

=a⁴+(ab)²+b⁴

=a⁴+2a²b²+b⁴-a²b²

=(a²+b²)²-(ab)²

=(a²+b²+ab)(a²+b²-ab)

=[(x+y)²+(x-y)²+(x+y)(x-y)][(x+y)²+(x-y)²-(x+y)(x-y)]

=(x²+2xy+y²+x²-2xy+y²+x²-y²)(x²+2xy+y²+x²-2xy+y²-x²+y²)

=(3x²+y²)(x²+3y²)