Viète's Formulas/Examples/Quartic

Example of Use of Viète's Formulas
Consider the quartic equation:
 * $x^4 + a_1 x^3 + a_2 x^2 + a_3 x + a_4 = 0$

Let its roots be denoted $x_1$, $x_2$, $x_3$ and $x_4$.

Then:

Proof
A specific instance of Viète's Formulas for $n = 4$.