\(\sqrt{25} = \sqrt[2]{25^{1}} = \underline{25^{1/2}} = 5\)What's under the radical has an implied or explicit exponent. This exponent is the numerator of the equivalent non-radical exponential fraction.
On the other hand, the implied or explicit number on the outside of the radical corresponds to the denominator of the equivalent non-radical exponential fraction.
\(\sqrt[3]{b^{2}} = b^{2/3}\)
\(\sqrt[3]{27} = \sqrt[3]{27^{1}} = \underline{27^{1/3}} = 3\)
