Вычислите \(\frac{9}{x}-\frac{9}{5x}\) при \(x=-2\).

Подставим \(x=-2\):

\(\frac{9}{-2}-\frac{9}{5\cdot(-2)}=-\frac{9}{2}-\left(-\frac{9}{10}\right)=-\frac{45}{10}+\frac{9}{10}=-\frac{36}{10}=-\frac{18}{5}=-3.6.\)

Ответ: \(-\frac{18}{5}\) (\(-3.6\)).