a) $$7^{\frac{3}{5}} = \sqrt[5]{7^3}$$
б) $$5x^{-\frac{2}{3}} = \frac{5}{x^{\frac{2}{3}}} = \frac{5}{\sqrt[3]{x^2}}$$
в) $$(6a)^{\frac{3}{7}} = \sqrt[7]{(6a)^3}$$
г) $$(x-y)^{\frac{1}{2}} = \sqrt{x-y}$$