Answer
-2
Work Step by Step
Based on the definition of $a^{\frac{m}{n}}$, we know that $a^{\frac{m}{n}}=\sqrt[n] a^{m}=(\sqrt[n] a)^{m}$ (where $\sqrt[n] a$ represents a real number).
Therefore, $\sqrt[4] (-2)^{4}=(-2)^{\frac{4}{4}}=(-2)^{1}=-2$.
