Đáp án:
$\begin{array}{l}
Dkxd:{x^2} - x - 6\# 0\\
\Leftrightarrow \left( {x - 3} \right)\left( {x + 2} \right)\# 0\\
\Leftrightarrow x\# 3;x\# - 2\\
P = \dfrac{{8{x^2} - 4{x^3}}}{{{x^2} - x - 6}}\\
P = 1\\
\Leftrightarrow \dfrac{{8{x^2} - 4{x^3}}}{{{x^2} - x - 6}} = 1\\
\Leftrightarrow 8{x^2} - 4{x^3} = {x^2} - x - 6\\
\Leftrightarrow 4{x^3} - 7{x^2} - x - 6 = 0\\
\Leftrightarrow x = 2,18\left( {tmdk} \right)\\
Vay\,x = 2,18\\
Khi:\left| {x - 5} \right| = 2\\
\Leftrightarrow \left[ \begin{array}{l}
x - 5 = 2\\
x - 5 = - 2
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l}
x = 7\left( {tm} \right)\\
x = 3\left( {ktm} \right)
\end{array} \right.\\
Khi:x = 7\\
\Leftrightarrow P = \dfrac{{{{8.7}^2} - {{4.7}^3}}}{{{7^2} - 7 - 6}}\\
= \dfrac{{ - 980}}{{36}}\\
= \dfrac{{ - 245}}{9}
\end{array}$
