$$x^4-8x^3+14x^2+8x-14 = 0$$
Answer
$$ \begin{matrix}x_1 = 0.93839 & x_2 = -0.97876 & x_3 = 3.06161 \\[1 em] x_4 = 4.97876 & \\[1 em] \end{matrix} $$
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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