The discriminant of a quadratic equation is a parameter that is used to determine the nature of the roots of the equation. The discriminant can be determined by b2- 4ac. The standard form of quadratic equation is ax2 + bx + c = 0. Upon substitution, we can easily determine the discriminant. If disc. is zero, the roots are equal; if <0, then the roots are positive and non-identical; if <0, the roots are negative and imaginary.