Find roots of polynomial $$ p(x) = -x^3+3x+7x+5 $$
Answer
The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.5135\\[1 em]x_2 &= -2.8741\\[1 em]x_3 &= 3.3876 \end{aligned} $$Explanation
Step 1:
Combine like terms:
$$ -x^3+ \color{blue}{3x} + \color{blue}{7x} +5 = -x^3+ \color{blue}{10x} +5 $$Step 2:
Polynomial $ -x^3+10x+5 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.
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