Đáp án:
5B
Giải thích các bước giải:
\(\begin{array}{l}
C5:\\
DK:x + 3 \ne 0 \to x \ne - 3\\
\to B\\
C6:\\
DK:\left\{ \begin{array}{l}
2 - x \ge 0\\
1 - 2x \ge 0
\end{array} \right.\\
\to \left\{ \begin{array}{l}
2 \ge x\\
\dfrac{1}{2} \ge x
\end{array} \right.\\
\to \dfrac{1}{2} \ge x\\
\to C\\
C7:\\
DK:\dfrac{{x + 1}}{{{{\left( {x - 2} \right)}^2}}} \ge 0\\
\to \left\{ \begin{array}{l}
x + 1 \ge 0\\
{\left( {x - 2} \right)^2} > 0
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x \ge - 1\\
x \ne 2
\end{array} \right.\\
\to D\\
C8:\\
DK:2x - 4 \ne 0 \to x \ne 2\\
2x + \dfrac{3}{{2x - 4}} < 3 + \dfrac{3}{{2x - 4}}\\
\to 2x < 3\\
\to x < \dfrac{3}{2};x \ne 2\\
\to B
\end{array}\)
