This Demonstration shows the discriminant of the polynomial . The discriminant of a polynomial of degree is the quantity , where is the derivative of and is the resultant of and . The resultant is equal to the determinant of the corresponding Sylvester matrix. The discriminant of is 0 if and only if has a multiple root.
The discriminant of a polynomial with leading coefficient 1 is the product over all pairs of roots , of .
The equation relates the discriminant and resultant.
To calculate the discriminant, we use the built-in Mathematica function Discriminant. The other way is to calculate the resultant using the Sylvester matrix and then the discriminant from the above equation.