An equation which has only three variable terms and is followed by two variable and one variable term is called a Trinomial equation.

This is also called a cubic equation. In other words, a polynomial equation which has a degree of three is called a cubic polynomial equation or trinomial polynomial equation.

Since the power of the variable is the maximum up to 3, therefore, we get three values for a variable, say x.

It is expressed as;

a(x^3) + b(x^2) + cx + d = 0