# How do you simplify sqrt3*3sqrt21?

May 17, 2018

$9 \sqrt{7}$

#### Explanation:

As you multiply roots, then the equation can become
$3 \sqrt{63}$
but we can take out the 3, making it
$9 \sqrt{7}$

May 17, 2018

$9 \sqrt{7}$

#### Explanation:

$\text{using the "color(blue)"law of radicals}$

•color(white)(x)sqrtaxxsqrtbhArrsqrt(ab)

$\Rightarrow \sqrt{3} \times 3 \times \sqrt{21} = 3 \times \sqrt{3 \times 21} = 3 \sqrt{63}$

$3 \sqrt{63} = 3 \left(\sqrt{9 \times 7}\right) = 3 \left(\sqrt{9} \times \sqrt{7}\right) = 3 \left(3 \sqrt{7}\right) = 9 \sqrt{7}$