#### Answer

The given radical expression, $
\sqrt[15]{x^5}
,$ is not simplified because the exponent in the radicand and the index of the radical have a $GCF$ equal to $5$.

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
Use the following conditions in checking if a radical is in simplest form:
1. The radicand has no factor raised to a power greater than or equal to the index.
2. The radicand has no fractions.
3. No denominator contains a radical.
4. Exponents in the radicand and the index of radical have greatest common factor 1.
$\bf{\text{Solution Details:}}$
The given radical expression, $
\sqrt[15]{x^5}
,$ is not simplified because the exponent in the radicand and the index of the radical have a $GCF$ equal to $5$.