a = 1, b = (-4) & c = (-3)
What do we do when we need to square root the -4 ?
First of all, if you evaluate , with the numbers you provided, you end up with . So no problem here, i guess.
In the other case of a square root of a negative number, you will have to work with Complex numbers. Let us suppose you have to solve . The next step is to write as . If solve this root, you get . Now we have
. Let's simplify all that and we get