4. Вычислите √ 125/7 ⋅ √20/7

$$\sqrt{\frac{125}{7}} \cdot \sqrt{\frac{20}{7}} = \sqrt{\frac{125 \cdot 20}{7 \cdot 7}} = \sqrt{\frac{2500}{49}} = \frac{\sqrt{2500}}{\sqrt{49}} = \frac{50}{7}$$

Ответ: $$\frac{50}{7}$$