Answer
$\sqrt 5$
Work Step by Step
We know from the radical form of $a^{\frac{m}{n}}$ that $a^{\frac{m}{n}}=\sqrt[n] a^{m}$ (where the indicated roots are real numbers).
Therefore, $\sqrt[4] 25=\sqrt[4] 5^{2}=5^{\frac{2}{4}}=5^{\frac{1}{2}}=\sqrt 5$
