а) $$\left(\frac{4}{5}\right)^2 = \frac{4}{5} \cdot \frac{4}{5} = \frac{4 \cdot 4}{5 \cdot 5} = \frac{16}{25}$$
б) $$\left(\frac{11}{15}\right)^2 = \frac{11}{15} \cdot \frac{11}{15} = \frac{11 \cdot 11}{15 \cdot 15} = \frac{121}{225}$$
в) $$\left(\frac{7}{6}\right)^3 = \frac{7}{6} \cdot \frac{7}{6} \cdot \frac{7}{6} = \frac{7 \cdot 7 \cdot 7}{6 \cdot 6 \cdot 6} = \frac{343}{216}$$
г) $$\left(\frac{3}{7}\right)^3 = \frac{3}{7} \cdot \frac{3}{7} \cdot \frac{3}{7} = \frac{3 \cdot 3 \cdot 3}{7 \cdot 7 \cdot 7} = \frac{27}{343}$$
д) $$\left(\frac{1}{4}\right)^3 = \frac{1}{4} \cdot \frac{1}{4} \cdot \frac{1}{4} = \frac{1 \cdot 1 \cdot 1}{4 \cdot 4 \cdot 4} = \frac{1}{64}$$
Ответ: а) 16/25, б) 121/225, в) 343/216, г) 27/343, д) 1/64