A cubic equation is a polynomial equation of degree three. The general formula for a cubic equation is y = Ax^3 + Bx^2 + Cx + D, with A-D being real constants. These equations have three complex roots and at least one of them is real. Cubics approach positive infinity in one direction and negative infinity in the other. They may have a local minimum and/or a local maximum, or neither. All cubics have one inflection point.