Question

（x的四次方+y的四次方）²-（2x²y²）

Answer 1

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

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

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

=(x^2+y^2)^2(x+y)^2(x-y)^2.