The root of polynomial $ p(x) $ is:
$$ \begin{aligned}x &= -\frac{ 1 }{ 2 } \end{aligned} $$Step 1:
Combine like terms:
$$ \color{blue}{3x} \color{blue}{-5x} -1 = \color{blue}{-2x} -1 $$Step 2:
$$ \begin{aligned} -2x-1 & = 0 \\[1 em] -2 \cdot x & = 1 \\[1 em] x & = \frac{ 1 }{ -2 } \end{aligned} $$