by A \(\begin{array}{l}
a)\,\,m > 3\\
b)\,\,m \ne 4
\end{array}\)
B \(\begin{array}{l}
a)\,\,m > 3\\
b)\,\,m \ne 1
\end{array}\)
C \(\begin{array}{l}
a)\,\,m \ge 3\\
b)\,\,\left\{ \begin{array}{l}
m \ne 1\\
m \ne 4
\end{array} \right.
\end{array}\)
D \(\begin{array}{l}
a)\,\,m > 3\\
b)\,\,\left\{ \begin{array}{l}
m \ne 1\\
m \ne 4
\end{array} \right.
\end{array}\)
Hướng dẫn Chọn đáp án là: D
Lời giải chi tiết:
\(\eqalign{& a)\,\,DK:\left\{ \matrix{m – 3 \ge 0 \hfill \cr m – 3 \ne 0 \hfill \cr} \right. \Leftrightarrow m > 3 \cr & b)\,\,DK:\left\{ \matrix{{{1 – m} \over {4 – m}} \ne 0 \hfill \cr 4 – m \ne 0 \hfill \cr} \right. \Leftrightarrow \left\{ \matrix{1 – m \ne 0 \hfill \cr 4 – m \ne 0 \hfill \cr} \right. \Leftrightarrow \left\{ \matrix{m \ne 1 \hfill \cr m \ne 4 \hfill \cr} \right. \cr} \)
