Chapter 9 - Roots and Radicals - 9.1 - Roots and Radicals - Problem Set 9.1 - Page 401: 77

$\approx26.5$

Using the properties of radicals, a rational approximation (to the nearest tenth) of the given expression, $ 8\sqrt{7}-4\sqrt{7}+6\sqrt{7} ,$ is \begin{array}{l}\require{cancel} (8-4+6)\sqrt{7} \\\\= 10\sqrt{7} \\\\ \approx26.5 .\end{array}