2) (-6b³/7c)²;

2) $$\left(-\frac{6b^3}{7c}\right)^2 = \frac{(-6b^3)^2}{(7c)^2} = \frac{36b^{3 \cdot 2}}{49c^2} = \frac{36b^6}{49c^2}$$

Ответ: 36b⁶/49c²