2) y^2/(x^2-xy) : (y/(x+y) - 2xy/(x^2-y^2)).

2) $$\frac{y^2}{x^2 - xy} : (\frac{y}{x+y} - \frac{2xy}{x^2 - y^2}) = \frac{y^2}{x(x-y)} : (\frac{y}{x+y} - \frac{2xy}{(x-y)(x+y)}) = \frac{y^2}{x(x-y)} : \frac{y(x-y) - 2xy}{(x-y)(x+y)} = \frac{y^2}{x(x-y)} : \frac{xy - y^2 - 2xy}{(x-y)(x+y)} = \frac{y^2}{x(x-y)} : \frac{-xy - y^2}{(x-y)(x+y)} = \frac{y^2}{x(x-y)} : \frac{-y(x+y)}{(x-y)(x+y)} = \frac{y^2}{x(x-y)} \cdot \frac{(x-y)(x+y)}{-y(x+y)} = \frac{y^2(x-y)(x+y)}{x(x-y)(-y)(x+y)} = \frac{y}{-x} = -\frac{y}{x}$$.

Ответ: $$- \frac{y}{x}$$