Đáp án:
$\begin{array}{l}
\left\{ \begin{array}{l}
y = - 2x + 1\left( {x \le 1} \right)\\
y = \dfrac{{x + 7}}{2}\left( {x > 1} \right)
\end{array} \right.\\
\Rightarrow TXĐ:D = R\\
+ Khi:x = 1\\
\Rightarrow y = - 2x + 1 = - 2.1 + 1 = - 1\\
+ Khi:x = 4\left( {x > 1} \right)\\
\Rightarrow y = \dfrac{{x + 7}}{2} = \dfrac{{4 + 7}}{2} = \dfrac{{11}}{2}\\
+ Khi:x = - 3\left( {x < 1} \right)\\
\Rightarrow y = - 2x + 1 = - 2.\left( { - 3} \right) + 1 = 7\\
+ Khi:x = 10\left( {x > 1} \right)\\
\Rightarrow y = \dfrac{{x + 7}}{2} = \dfrac{{10 + 7}}{2} = \dfrac{{17}}{2}\\
+ Khi:x = - 4\left( {x < 1} \right)\\
\Rightarrow y = - 2x + 1 = - 2.\left( { - 4} \right) + 1 = 9
\end{array}$
