Question

On simplifying the expression $\sqrt{45}-3\sqrt{20}+3\sqrt{5}$ we get ___.

Answer 1

$\sqrt{45}-3\sqrt{20}+3\sqrt{5}$
$=\sqrt{9\times 5}-3\sqrt{4\times 5}+3\sqrt{5}$
$=\sqrt{9}\times \sqrt{5}-3\sqrt{4}\times \sqrt{5}+3\sqrt{5}$
$=3\sqrt{5}-3\times 2\times \sqrt{5}+3\sqrt{5}$
$=3\sqrt{5}-6\sqrt{5}+3\sqrt{5}$
$=6\sqrt{5}-6\sqrt{5}$
$=0$