Given an equation ax^2+bx+c=0
what values a,b cause the roots of the equation to be a and b and the discriminant to be equal to c?

I am aware that if the discriminant is positive there are two real solutions, if 0 there is 1 real solution, if negative there are no real solutions.

What does it mean if the discriminant is complex? Same as negative? 1 or 2 imaginary solutions? Can I tell whether the number of imaginary solutions is 1 or 2 based on looking at the discriminant? Thought I would ask, instead of looking it up...