Book:Murray R. Spiegel/Mathematical Handbook of Formulas and Tables/Chapter 9/Quartic Equation

Quartic Equation $x^4 + a_1 x^3 + a_2 x^2 + a_3 x + a_4 = 0$

 * Quartic Equation
 * $9.6$, $9.7$: Ferrari's Method
 * $9.8$: Viète's Formula for Quartic Equation