Answer
$-4\sqrt{5}+7\sqrt{10}$
Work Step by Step
The given expression is
$=2\sqrt{5}+7\sqrt{10}-3\sqrt{20}$
Factor as square terms.
$=2\sqrt{5}+7\sqrt{10}-3\sqrt{4\cdot 5}$
Use product property of square roots.
$=2\sqrt{5}+7\sqrt{10}-3\sqrt{4}\cdot \sqrt{5}$
Simplify.
$=2\sqrt{5}+7\sqrt{10}-3(2)\sqrt{5}$
$=2\sqrt{5}+7\sqrt{10}-6\sqrt{5}$
$=2\sqrt{5}-6\sqrt{5}+7\sqrt{10}$
Use distributive property.
$=(2-6)\sqrt{5}+7\sqrt{10}$
Simplify.
$=-4\sqrt{5}+7\sqrt{10}$
