The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 0\\[1 em]x_2 &= 2.5963\\[1 em]x_3 &= -0.0963 \end{aligned} $$Step 1:
Factor out $ \color{blue}{ x^2 }$ from $ 4x^4-10x^3-x^2 $ and solve two separate equations:
$$ \begin{aligned} 4x^4-10x^3-x^2 & = 0\\[1 em] \color{blue}{ x^2 }\cdot ( 4x^2-10x-1 ) & = 0 \\[1 em] \color{blue}{ x^2 = 0} ~~ \text{or} ~~ 4x^2-10x-1 & = 0 \end{aligned} $$One solution is $ \color{blue}{ x = 0 } $. Use second equation to find the remaining roots.
Step 2:
The solutions of $ 4x^2-10x-1 = 0 $ are: $ x = \dfrac{ 5 }{ 4 }-\dfrac{\sqrt{ 29 }}{ 4 } ~ \text{and} ~ x = \dfrac{ 5 }{ 4 }+\dfrac{\sqrt{ 29 }}{ 4 }$.
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