How do you simplify #sqrt(-50)#?
Here you have a problem...
in fact you cannot solve a square root with a negative argument or, better, you cannot find a real number which is solution of your square root.
What you can do it is try to find a solution somewhere else...in the place of imaginary numbers!
First of all you manipulate your root as:
you now introduce a new entity: the imaginary unit
so you can write:
1] solution of your problem; in fact if you square it you get:
2] it is an imaginary number (it contains