3. Сократите дробь: a) 5-√5; √10-√2 б) b-4 √b-2.

а) Сократим дробь $$\frac{5-\sqrt{5}}{\sqrt{10}-\sqrt{2}}$$:

$$\frac{5-\sqrt{5}}{\sqrt{10}-\sqrt{2}} = \frac{\sqrt{5}(\sqrt{5}-1)}{\sqrt{2}(\sqrt{5}-1)} = \frac{\sqrt{5}}{\sqrt{2}} = \frac{\sqrt{5}\sqrt{2}}{\sqrt{2}\sqrt{2}} = \frac{\sqrt{10}}{2}$$.

Ответ: $$\frac{\sqrt{10}}{2}$$

б) Сократим дробь $$\frac{b-4}{\sqrt{b}-2}$$:

$$\frac{b-4}{\sqrt{b}-2} = \frac{(\sqrt{b}-2)(\sqrt{b}+2)}{\sqrt{b}-2} = \sqrt{b}+2$$.

Ответ: $$\sqrt{b}+2$$