The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0.7937\\[1 em]x_2 &= -0.3969+0.6874i\\[1 em]x_3 &= -0.3969-0.6874i \end{aligned} $$Step 1:
Get rid of fractions by multipling equation by $ \color{blue}{ 2 } $.
$$ \begin{aligned} x^3-\frac{1}{2} & = 0 ~~~ / \cdot \color{blue}{ 2 } \\[1 em] 2x^3-1 & = 0 \end{aligned} $$Step 2:
Polynomial $ 2x^3-1 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.