1) $$\left(\frac{a^7}{b^2}\right)^3 = \frac{(a^7)^3}{(b^2)^3} = \frac{a^{7 \cdot 3}}{b^{2 \cdot 3}} = \frac{a^{21}}{b^6}$$
Ответ: $$\frac{a^{21}}{b^6}$$