The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.8762\\[1 em]x_2 &= 2.1724\\[1 em]x_3 &= -3.5462 \end{aligned} $$Polynomial $ 4x^3+9x^2-26x-27 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.