# How do you multiply  (-6sqrt3)(-2sqrt15)?

Jun 27, 2015

I found: $36 \sqrt{5}$

#### Explanation:

You can first multiply the numbers outside AND inside the roots:
$\left(- 6\right) \cdot \left(- 2\right) \sqrt{3 \cdot 15} = 12 \sqrt{45} =$
Then manipulate inside the root:
$= 12 \sqrt{5 \cdot 9} =$
Take out $9$ from the root as $3$:
$= 12 \cdot 3 \sqrt{5} = 36 \sqrt{5}$