Chapter 9 - Roots and Radicals - 9.1 - Roots and Radicals - Problem Set 9.1 - Page 401: 69

$-9\sqrt{7}-2\sqrt{10}$

Using the Distributive Property, the given expression, $ 6\sqrt{7}+5\sqrt{10}-8\sqrt{10}-4\sqrt{7}-11\sqrt{7}+\sqrt{10} ,$ simplifies to \begin{array}{l}\require{cancel} (6\sqrt{7}-4\sqrt{7}-11\sqrt{7})+(5\sqrt{10}-8\sqrt{10}+\sqrt{10}) \\\\= (6-4-11)\sqrt{7}+(5-8+1)\sqrt{10} \\\\= -9\sqrt{7}-2\sqrt{10} .\end{array}