Question

x的4次方+x的平方y的平方-2y的4次方

Answer 1

答：

x^4+x²y²-2y^4

=(x^4-y^4)+x²y²-y^4

=(x²+y²)(x²-y²)+(x²-y²)y²

=(x²+2y²)(x-y)(x+y)