# Question #d169c

Sep 7, 2016

It is undefined - it is an imaginary/non-real number.

#### Explanation:

The 4th root is the same as the square root of a square root.

$\sqrt{\sqrt{-} 16}$ is undefined because it is a non-real or imaginary number.

It is not possible to find any even root of a negative number.

To deal with this further requires using complex numbers.