原式=(x²+y²)(x²-y²)-x²(x²-y²) =（x²-y²)（x²+y²-x²） =y²（x+y）(x-y) 望采纳，谢谢
解：原式＝﹙x²－y²﹚﹙x²＋y²－x²﹚ ＝x²﹙x－y﹚﹙x＋y﹚.
(x²+y²)(x²-y²)-x²(x+y)(x-y)=（x²-y²)（x²+y²-x²）=y^2（x+y）(x-y)
