#### Answer

$x^3$

#### Work Step by Step

Using the rule given in the book:
If $n$ is an even positive integer, then $\sqrt[n]{a^n} = |a|$
If $n$ is an odd positive integer, then $\sqrt[n]{a^n} = a$
We get $\sqrt{x^6} = \sqrt{(x^3)^2} \rightarrow |x^3| = x^3$