# How do you simplify square root of -10 times the root of -40?

Sep 10, 2015

sqrt(-10) * sqrt(-40) = color(green)(20

#### Explanation:

square root of -10 times the root of -40 can be written as :

$\sqrt{- 10} \cdot \sqrt{- 40}$

One of the rules in Exponents says that color(blue)(sqrta*sqrtb=sqrt(ab)

Hence $\sqrt{- 10} \cdot \sqrt{- 40} = \sqrt{- 10 \cdot - 40}$

$= \sqrt{400}$

$= \sqrt{20 \cdot 20}$

=color(green)(20

PS: It can also be equal to $- 20$, but color(green)(20 is the principal square root.