Biết rằng bất phương trình \(\left\{ \begin{array}...

D

- Hướng dẫn giải

\(BPT \Leftrightarrow\left\{ \begin{array}{l}
x - 1 < 2x - 3\\
5 - 3x \le 2x - 6\\
3x \le x + 5
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
2 < x\\
11 \le 5x\\
2x \le 5
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x > 2\\
x \ge \frac{{11}}{5}\\
x \le \frac{5}{2}
\end{array} \right. \Leftrightarrow \frac{{11}}{5} \le x \le \frac{5}{2}\)

Suy ra \(a + b = \frac{{11}}{5} + \frac{5}{2} = \frac{{47}}{{10}}.\)