Find roots of polynomial $$ p(x) = 92+70x+20x^2+90x^3 $$
Answer
The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.8128\\[1 em]x_2 &= 0.2953+1.0819i\\[1 em]x_3 &= 0.2953-1.0819i \end{aligned} $$Explanation
Step 1:
Write polynomial in descending order
$$ \begin{aligned} 92+70x+20x^2+90x^3 & = 0\\[1 em] 90x^3+20x^2+70x+92 & = 0 \end{aligned} $$Step 2:
Polynomial $ 90x^3+20x^2+70x+92 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.
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