A quartic equation is the result of setting a quartic function to zero, an example quartic equation is the equation
It is the highest degree of polynomial equation for which exact values of the roots can be found, by taking nth roots, and use of the normal algebraic operators.
If a0=0, then one of the roots is x=0, and the other roots can be found, by dividing by x, and solving the resulting cubic equation, a4x³+a3x²+a2x+a1=0.
Otherwise, divide the equation by a4, to get an equation of the form