Đáp án:
$\begin{array}{l}
P = \dfrac{1}{2} - \dfrac{1}{2}\left( {x:\dfrac{1}{6} - \dfrac{1}{4}} \right) - 2\left| {x - 2} \right|\\
= \dfrac{1}{2} - \dfrac{1}{2}\left( {6x - \dfrac{1}{4}} \right) - 2\left| {x - 2} \right|\\
= \dfrac{1}{2} - 3x + \dfrac{1}{8} - 2\left| {x - 2} \right|\\
= \dfrac{5}{8} - 3x - 2\left| {x - 2} \right|\\
a)x \ge 2\\
\Leftrightarrow \left| {x - 2} \right| = x - 2\\
\Leftrightarrow P = \dfrac{5}{8} - 3x - 2\left( {x - 2} \right)\\
= \dfrac{5}{8} - 3x - 2x + 4\\
= \dfrac{{37}}{8} - 5x\\
b)x < 2\\
\Leftrightarrow \left| {x - 2} \right| = 2 - x\\
\Leftrightarrow P = \dfrac{5}{8} - 3x - 2\left( {2 - x} \right)\\
= \dfrac{5}{8} - 3x - 4 + 2x\\
= \dfrac{{ - 27}}{8} - x
\end{array}$
