(x的4次方-y的4次方)除以(x方+y方)/(x+y)乘以1/(x+y)的平方

问题描述:

(x的4次方-y的4次方)除以(x方+y方)/(x+y)乘以1/(x+y)的平方

原式=(x²+y²)(x²-y²)×(x+y)/(x²+y²)×1/(x+y)²
=(x²-y²)/(x+y)
=x-y