The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -2.9033\\[1 em]x_2 &= 1.4517+4.465i\\[1 em]x_3 &= 1.4517-4.465i \end{aligned} $$Polynomial $ 127x^3+1729x+8128 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.