An "imaginary number" is a multiple of a quantity called "[i]i[/i]" which is defined by the property that [i]i[/i] squared equals -1. This is puzzling to most people, because it is hard to imagine any number having a negative square. The result: it is tempting to believe that [i]i[/i] doesn't really exist, but is just a convenient mathematical fiction. [br][br]the discriminant helps tell you the number of real solutions to a quadratic equation. The expression used to find the discriminant is the expression located under the radical in the quadratic formula! In this tutorial, get introduced to the discriminant of a quadratic equation!