Chapter 9 - Roots and Radicals - 9.1 - Roots and Radicals - Problem Set 9.1 - Page 401: 72

$28.3$

Using the properties of radicals, a rational approximation (to the nearest tenth) of the given expression, $ 6\sqrt{2}+14\sqrt{2} ,$ is \begin{array}{l}\require{cancel} (6+14)\sqrt{2} \\\\= 20\sqrt{2} \\\\ \approx 28.3 .\end{array}