# What is the square root of 3 times square root of 15?

Sep 16, 2015

$3 \sqrt{5}$

#### Explanation:

$\sqrt{3} \sqrt{15}$

$\sqrt{a} \sqrt{b} = \sqrt{a} b$

$\sqrt{3} \sqrt{5} = \sqrt{45}$

Factor $45$.

$\sqrt{3 \times 3 \times 5} =$

$\sqrt{{3}^{2} \times 5}$

$\sqrt{{a}^{2}} = a$.

$\sqrt{{3}^{2}} = 3$

$\sqrt{{3}^{2} \times 5} =$

$3 \sqrt{5}$