So under the square root number is a negative 8. Should be 2*sqr root of 2. How to they get there? Where does imaginary symbol go usually? Any video links,sites, diagrams will be helpful plz.
Hey Melcarthus.
The simplest answer is to use the polar form of a complex number and use the rules of exponentiation.
Complex number - Wikipedia, the free encyclopedia
This is one of the first things you should have learnt when studying imaginary numbers...
$\displaystyle \sqrt{-8} = \sqrt{8} \cdot \sqrt{-1} = \sqrt{8}i = 2 \sqrt{2}i$
The i is not under the square root.
The title is also quite misleading. You are trying to find the square root of a negative number, not the square root of an imaginary number. It's more complicated when you are trying to find the square root of an imaginary number.