Answer
$\frac{\sqrt {13z}}{\sqrt {13z}}$
Work Step by Step
Appropriate form of $1$ that can be used as a factor to eliminate the radical in the denominator is $\frac{\sqrt {13z}}{\sqrt {13z}}$:
$\frac{1}{\sqrt{13z}}=\frac{1}{\sqrt{13z}}\times\frac{\sqrt{13z}}{\sqrt{13z}}=\frac{\sqrt{13z}}{13z}$
