因式分解a(x^2+2xy)^2-ay^4
问题描述：
因式分解a(x^2+2xy)^2-ay^4
答
a(x^2+2xy)^2-ay^4
=a(x^2+2xy-y^2)(x^2+2xy+y^2)
=a(x^2+2xy-y^2)(x+y)^2