Use the simple Quartic formula provided below to find the roots of a biquadratic equation. In quartic equation formula, the largest exponent is four ie, 4^thdegree equation. The equation is ax⁴ + bx³ + cx² + dx + e = 0. Here a, b, c and d are the root values. Quartic is the polynomial which can be solved using any of the methods such as factoring, completing the square, rational root theorem, using a graphing calculator, or by using the quadratic formula.