[2x^2-(x+y)(x-y)][(-x-y)(y-x)+2y^2]
=（2x²-x²+y²）(x²-y²+2y²)
=(x²+y²)(x²+y²)
=x^4+2x²y²+y^4
如追加其它问题,采纳本题后点击想我求助,