## Intermediate Algebra (12th Edition)

$-6\sqrt{10}$
$\bf{\text{Solution Outline:}}$ To simplify the given radical expression, $6\sqrt{10}-12\sqrt{10} ,$ combine the like terms. $\bf{\text{Solution Details:}}$ By combining like terms, the expression above is equivalent to \begin{array}{l}\require{cancel} (6-12)\sqrt{10} \\\\= -6\sqrt{10} .\end{array}