x3+x2-y3-y2
=x3-y3+x2-y2
=(x-y)(x²+xy+y²)+(x-y)(x+y)
=(x-y)(x+y+x²+xy+y²)为什么x3-y3=(x-y)(x2+xy+y2)??亲，这是立方差公式，不需要你证明的。你只要熟记就行了。