Answer
$\dfrac{3\sqrt[]{3a}}{a}$
Work Step by Step
Rationalizing the denominator of $
\dfrac{9}{\sqrt[]{3a}}
$ results to
\begin{array}{l}
\dfrac{9}{\sqrt[]{3a}}
\cdot
\dfrac{\sqrt[]{3a}}{\sqrt[]{3a}}
\\\\=
\dfrac{9\sqrt[]{3a}}{\sqrt[]{9a^2}}
\\\\=
\dfrac{9\sqrt[]{3a}}{3a}
\\\\=
\dfrac{3\sqrt[]{3a}}{a}
.\end{array}