16. \(\frac{(x-y)^2}{(x-y)(x+y)}=\)

Сокращаем на \(x-y\): \(\frac{(x-y)^2}{(x-y)(x+y)}=\frac{x-y}{x+y}\), \(x\ne y\), \(x\ne-y\).

Ответ: \(\frac{x-y}{x+y}\)