$$(\frac{x+y}{x-y}-\frac{x-y}{x+y})\cdot\frac{x+y}{x-y}+\frac{x-y}{x+y})^{--1}$$
$\frac{x^{3}+7xy^{2}-y^{3}+yx^{2}}{\left(x+y\right)\left(x-y\right)^{2}}$
