Question

How do you simplify `sqrt(-81x^6)`?

Answer 1

First you factorize the argument and get any squares out.
Remember `sqrt(a*b)=sqrta*sqrtb`

Explanation:

`=sqrt(-1*9^2*(x^3)^2)`
`=sqrt(-1)*sqrt(9^2)*sqrt((x^3)^2)`

`=i*9*x^3=9x^3i`