Answer
16
Work Step by Step
As shown on page 445, we know that $a^{\frac{m}{n}}=\sqrt[n] a^{m}=(\sqrt[n] a)^{m}$.
Therefore, $(-8)^{\frac{4}{3}}=\sqrt[3] (-8)^{4}=(\sqrt[3] -8)^{4}=(-2)^{4}=16$.
We know that $\sqrt[3] -8=-2$, because $(-2)^{3}=-8$.