$$x^3+x^2+3x+12 = 0$$
Answer
$$ \begin{matrix}x_1 = -2.16848 & x_2 = 0.58424+2.2787i & x_3 = 0.58424-2.2787i \end{matrix} $$
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