$$-s^4-6s^3+5s^2+99s+86 = 0$$
Answer
$$ \begin{matrix}s_1 = -0.96035 & s_2 = 3.79019 & s_3 = -4.41492+2.03356i \\[1 em] s_4 = -4.41492-2.03356i & \\[1 em] \end{matrix} $$
Explanation
This polynomial has no rational roots that can be found using Rational Root Test.
Roots were found using quartic formulas
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