Срочно!!!!!!! Помогите решить примееееррр

[latex] (\dfrac{x^2}{y} - 3x - \dfrac{y^2}{x} + 3y) \cdot \dfrac{xy}{x^2 - y^2} = (\dfrac{x^3 - y^3}{xy} - 3(x - y)) \cdot \dfrac{xy}{(x - y)(x + y)} \\ \\ = \dfrac{(x - y)(x^2 + xy + y^2)- 3xy(x - y)}{xy} \cdot \dfrac{xy}{(x - y)(x + y)} = \\ \\ = \dfrac{(x - y)(x^2 + xy + y^2 - 3xy)xy}{xy(x - y)(x + y)} = \\ \\ = \dfrac{(x - y)^2}{x + y } [/latex]