Discriminant

The Discriminant of a Quadratic Equation of the form ax^2+bx+c=0 (sorry, LaTeX isn't working for me) is the quantity $b^2-4ac$ . When a, b, and c are real, this is a notable quantity, because if the Discriminant is positive, the equation has two real roots; if the discriminant is negative, the equation has two non-real roots; and if the discriminant is 0, the equation has a real double root.