Answer
$3x\sqrt{5x}$
Work Step by Step
Using $\sqrt{x}\cdot\sqrt{y}=\sqrt{xy}$ or the product rule of radicals, the given expression, $
\sqrt{15x^2}\cdot\sqrt{3x}
,$ is equivalent to
\begin{array}{l}\require{cancel}
\sqrt{15x^2(3x)}
\\\\=
\sqrt{45x^3}
\\\\=
\sqrt{9x^2\cdot5x}
\\\\=
\sqrt{(3x)^2\cdot5x}
\\\\=
3x\sqrt{5x}
.\end{array}
Note that variables are assumed to have positive real numbers.
