Answer
$\textbf{rationalizing the denominator}$
Work Step by Step
Recall:
A radical expression that has a radical in its denominator is not yet in lowest terms.
Such a radical expression can be reduced to lowest terms using the process called $\textbf{rationalizing the denominator}$.
Thus, the missing expression in the given statement is $\textbf{rationalizing the denominator}$.
