The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= \frac{ 15 }{ 2 }\\[1 em]x_2 &= -1 \end{aligned} $$The solutions of $ -16x^2+104x+120 = 0 $ are: $ x = -1 ~ \text{and} ~ x = \dfrac{ 15 }{ 2 }$.
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