Question

（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

Answer 1

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

=(x²-y²)/(x+y)

=x-y