Chapter 9 - Roots and Radicals - 9.1 - Roots and Radicals - Problem Set 9.1 - Page 401: 74

$\approx 14.7 $

Using the properties of radicals, a rational approximation (to the nearest tenth) of the given expression, $ 18\sqrt{6}-12\sqrt{6} ,$ is \begin{array}{l}\require{cancel} (18-12)\sqrt{6} \\\\= 6\sqrt{6} \\\\ \approx 14.7 .\end{array}