Answer
$-5x$
Work Step by Step
RECALL:
(i) $\sqrt[n]{a^n} = a$ when $n$ is odd
(ii) $\sqrt[n]{a^n}=|a|$ when $n$ is even
Write the expression inside the radical sign as a cube, and then use rule (i) above to obtain:
$\sqrt[3]{(-5x)^3}=-5x$