Cubic Equation Solver

Mathematics

Solve general cubic polynomial equations (ax³ + bx² + cx + d = 0) with Cardano's analytic formulas. Compute all real and complex conjugate roots with discriminant classification.

Calculated Result
3, 1, 2

3 real root(s)

Formula: ax³ + bx² + cx + d = 0

About this calculator

Cubic equations model cubic volume optimizations, thermodynamic equations of state (such as Van der Waals gas laws), and structural deflection curves under non-uniform beam loading.

This calculator computes all 3 roots of any third-degree polynomial with real coefficients, classifying whether the roots are three distinct real numbers, repeated real numbers, or one real root accompanied by two complex conjugate roots.

How It Works & Formula

Formulaax³ + bx² + cx + d = 0 (Cardano / trigonometric identity)

The polynomial is depressed to t³ + pt + q = 0 by substituting x = t - b/(3a). Cardano's discriminant Δ = (q/2)² + (p/3)³ determines the nature of the roots via trigonometric or hyperbolic solutions.