Yes, if sign on the right is (-) it inverts the sign on the left.
so if you want to maintain the sign in this state you use Abs(right-side);
So..
MySqrt(-16)*Abs(Mysqrt(-16)) = -16;
a basic short cut to making a number reverse sign is to simply multiply it by -1
I am sure you've seen that somewhere
at least that is how I understand it anyway.
At least it should be