$$2s^3+12s^2+18s+6 = 0$$
Answer
$$ \begin{matrix}s_1 = -0.46791 & s_2 = -1.6527 & s_3 = -3.87939 \end{matrix} $$
Explanation
This polynomial has no rational roots that can be found using Rational Root Test.
Roots were found using qubic formulas.
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Polynomial Equations Solver