Answer
$\color{blue}{-3(5^{1/2})(p^{3/2})}$
Work Step by Step
RECALL:
(1) $a^{m/n}=\sqrt[n]{a^m} = (\sqrt[n]{a})^m$
(2) $(ab)^m=a^mb^m$
Use rule (1) above to obtain:
$-3\sqrt{5p^3}
\\=-3(5p^3)^{1/2}$
Use rule (2) above to obtain:
$= \color{blue}{-3(5^{1/2})(p^{3/2})}$
