64^{-\frac{4}{3 a.\ \dfrac{1}{256}\ b.\ \dfrac{1}{(\sqrt[3]{64})^4}\ c.\ \sqrt[3]{64^{-4\ d.\ -256 Simplify the following radical expression: 4 sqrt (625) Simplify the following radical expression : 4 \sqrt {\frac{(81)}{(16) a) \frac{2}{3} \b) \frac{3...