Chapter 7 - Section 7.5 - Rationalizing Denominators and Numerators of Radical Expressions - Exercise Set - Page 445: 18

$\dfrac{-5\sqrt[]{22}}{11}$

Rationalizing the denominator of $ \dfrac{-5\sqrt{2}}{\sqrt[]{11}} $ results to \begin{array}{l} \dfrac{-5\sqrt{2}}{\sqrt[]{11}} \cdot \dfrac{\sqrt[]{11}}{\sqrt[]{11}} \\\\= \dfrac{-5\sqrt[]{22}}{\sqrt[]{121}} \\\\= \dfrac{-5\sqrt[]{22}}{11} .\end{array}