Answer
$5x^3+30x^2-10x$
Work Step by Step
Using $a(b+c)=ab+ac$ or the Distributive Property, the given expression, $
5x(x^2+6x-2)
$, is equivalent to
\begin{array}{l}\require{cancel}
5x(x^2)+5x(6x)+5x(-2)
\\\\=
5x^3+30x^2-10x
.\end{array}