The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.3465\\[1 em]x_2 &= 2.2778\\[1 em]x_3 &= 5.0687 \end{aligned} $$Polynomial $ x^3-7x^2+9x+4 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.