5. Найдите значение выражения x⁵y-xy⁵ 2(x-3y) 5(3y-x) x⁴-y⁴ при х=-¹/₇ и у=-14.

\[\begin{aligned} \frac{x^5y - xy^5}{5(3y-x)} \cdot \frac{2(x-3y)}{x^4 - y^4} &= \frac{xy(x^4 - y^4)}{5(3y-x)} \cdot \frac{2(x-3y)}{x^4 - y^4} \\ &= \frac{xy \cdot 2(x-3y)}{5(3y-x)} \\ &= \frac{2xy(x-3y)}{-5(x-3y)} \\ &= -\frac{2xy}{5} \end{aligned}\]

\[\begin{aligned} -\frac{2xy}{5} &= -\frac{2 \cdot (-\frac{1}{7}) \cdot (-14)}{5} \\ &= -\frac{\frac{28}{7}}{5} \\ &= -\frac{4}{5} \\ &= -0.8 \end{aligned}\]