The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 1.0714\\[1 em]x_2 &= -4.3269\\[1 em]x_3 &= 6.2554 \end{aligned} $$Polynomial $ x^3-3x^2-25x+29 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.