Answer
$\color{blue}{\huge{x^3 +5x}}$
Work Step by Step
$x(x^2 + 5) \ne x^3 +5$
Lets work this through.
$\color{blue}{x}(x^2 + 5) = \color{blue}{x}(x^2) +\color{blue}{x}(5)$
$x(x^2) +x(5) = x^3 +5x$
$\color{blue}{\huge{x^3 +5x}}$