Cardano's formula

A cubic equation is an equation involving a cubic polynomial, i.e., one of the form a_3 x^3 + a_2 x^2 + a_1 x + a_0 = 0. Since a_3 !=0 (or else the polynomial would be quadratic and not cubic), this can without loss of generality be divided through by a_3, giving x^3 + a_2^, x^2 + a_1^, x + a_0^, = 0. A closed-form formula known as the cubic formula exists for the solutions of a cubic equation.

casus irreducibilis | cubic formula | cubic polynomial