Đáp án:
$\begin{array}{l}
b)Dkxd:\left\{ \begin{array}{l}
2x - 3m + 4 \ge 0\\
x + m - 1 \ne 0
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
x \ge \dfrac{{3m - 4}}{2}\\
x \ne 1 - m
\end{array} \right.\\
Do:TXD = \left[ {0; + \infty } \right)hay\,x \ge 0\\
\Rightarrow \left\{ \begin{array}{l}
\dfrac{{3m - 4}}{2} = 0\\
1 - m < 0
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
m = \dfrac{4}{3}\\
m > 1
\end{array} \right.\\
\text{Vậy}\,m = \dfrac{4}{3}
\end{array}$
