Answer
$\dfrac{5\sqrt{m-n}}{m-n}$
Work Step by Step
$\bf{\text{Solution Outline:}}$
To rationalize the denominator of the given expression, $
\dfrac{5}{\sqrt{m-n}}
,$ multiply both the numerator and the denominator by the denominator.
$\bf{\text{Solution Details:}}$
Multiplying both the numerator and the denominator by the denominator, the given expression is equivalent to
\begin{array}{l}\require{cancel}
\dfrac{5}{\sqrt{m-n}}\cdot\dfrac{\sqrt{m-n}}{\sqrt{m-n}}
\\\\=
\dfrac{5\sqrt{m-n}}{(\sqrt{m-n})^2}
\\\\=
\dfrac{5\sqrt{m-n}}{m-n}
.\end{array}
