5. (x - y) x+y Vx-y

5. $$(x - y) \frac{x+y}{\sqrt{x-y}} = \frac{(x - y)(x+y)}{\sqrt{x-y}} = \frac{(x - y)(x+y) \sqrt{x-y}}{x-y} = (x+y)\sqrt{x-y}$$ Ответ: $$(x+y)\sqrt{x-y}$$