Đáp án:
Chọn B.
Giải thích các bước giải:
\(\begin{array}{l}
Dua\,\,\,vao\,\,dths \Rightarrow \left\{ \begin{array}{l}
f\left( x \right) > 0\, \Leftrightarrow x \in \left( { - 1;\,1} \right) \cup \left( {2;\,\,4} \right)\\
f\left( x \right) < 0 \Leftrightarrow x \in \left( { - \infty ;\, - 1} \right) \cup \left( {1;\,\,2} \right) \cup \left( {4; + \infty } \right)
\end{array} \right..\\
g\left( x \right) = f\left( {1 - x} \right)\\
\Rightarrow g'\left( x \right) = - f'\left( {1 - x} \right).\\
\Rightarrow hs\,\,g\left( x \right)\,\,\,DB \Leftrightarrow - f'\left( {1 - x} \right) > 0\\
\Leftrightarrow f'\left( {1 - x} \right) < 0\\
\Leftrightarrow \left[ \begin{array}{l}
1 - x < - 1\\
1 < 1 - x < 2\\
1 - x > 4
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x > 2\\
- 1 < x < 0\\
x < - 3
\end{array} \right.\\
\Rightarrow Chon\,\,B.
\end{array}\)
