Решение
1) (y /(x + y) - (2xy) / [(x - y)*(x + y)] = [y*(x - y) - 2xy] / ([x - y)*(x + y)] =
= - (xy + y²) / [(x - y)*(x + y)] = - [y*(x + y)] / [(x - y)*(x + y)] =
= - y / (x - y)
2) y² / [x*(x - y)] : [ - y / (x - y)] = [y² * (x - y)] / [ - y * x*(x - y)] = - y / x