The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0\\[1 em]x_2 &= -1\\[1 em]x_3 &= -7 \end{aligned} $$Step 1:
Factor out $ \color{blue}{ 2x }$ from $ 2x^3+16x^2+14x $ and solve two separate equations:
$$ \begin{aligned} 2x^3+16x^2+14x & = 0\\[1 em] \color{blue}{ 2x }\cdot ( x^2+8x+7 ) & = 0 \\[1 em] \color{blue}{ 2x = 0} ~~ \text{or} ~~ x^2+8x+7 & = 0 \end{aligned} $$One solution is $ \color{blue}{ x = 0 } $. Use second equation to find the remaining roots.
Step 2:
The solutions of $ x^2+8x+7 = 0 $ are: $ x = -7 ~ \text{and} ~ x = -1$.
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