x+y分之x的立方-y的立方除以2x+2y分之x的平方+xy+y的平方

问题描述:

x+y分之x的立方-y的立方除以2x+2y分之x的平方+xy+y的平方

=(x-y)(x²+xy+y²)/(x+y) ×2(x+y)/(x²+xy+y²)
=2(x-y)
=2x-2y