в) \(\frac{1}{\sqrt{x}-\sqrt{y}} = \frac{\sqrt{x}+\sqrt{y}}{(\sqrt{x}-\sqrt{y})(\sqrt{x}+\sqrt{y})} = \frac{\sqrt{x}+\sqrt{y}}{x-y}\)
Ответ: \(\frac{\sqrt{x}+\sqrt{y}}{x-y}\)