$$-x^3+14x+12 = 0$$
Answer
$$ \begin{matrix}x_1 = -0.91118 & x_2 = -3.20191 & x_3 = 4.11309 \end{matrix} $$
Explanation
This polynomial has no rational roots that can be found using Rational Root Test.
Roots were found using qubic formulas.
This page was created using
Polynomial Equations Solver