17. $$\frac{a}{(a-b)^2} + \frac{2}{3(a-b)} =$$

$$\frac{a}{(a-b)^2} + \frac{2}{3(a-b)} = \frac{3a}{3(a-b)^2} + \frac{2(a-b)}{3(a-b)^2} = \frac{3a + 2a - 2b}{3(a-b)^2} = \frac{5a - 2b}{3(a-b)^2}$$ Ответ: $$\frac{5a - 2b}{3(a-b)^2}$$