7) 8√n/8=

$$8\sqrt{\frac{n}{8}} = 8\frac{\sqrt{n}}{\sqrt{8}} = 8\frac{\sqrt{n}}{2\sqrt{2}} = 4\frac{\sqrt{n}}{\sqrt{2}} = 4\frac{\sqrt{n}\cdot\sqrt{2}}{\sqrt{2}\cdot\sqrt{2}} = 4\frac{\sqrt{2n}}{2} = 2\sqrt{2n}$$

Ответ: $$2\sqrt{2n}$$