1. ab +√ab a-b

1. $$\frac{\sqrt{ab}}{a + \sqrt{ab}} \cdot \frac{\sqrt{ab} - a}{\sqrt{ab} - a} = \frac{\sqrt{ab}(\sqrt{ab} - a)}{(a + \sqrt{ab})(\sqrt{ab} - a)} = \frac{ab - a\sqrt{ab}}{ab - a^2} = \frac{ab - a\sqrt{ab}}{ab - a^2}$$ Ответ: $$\frac{ab - a\sqrt{ab}}{ab - a^2}$$