a) \(\left\{ \begin{array}{l}2m - 1 > 0\\{m^2} - (m - 2)(2m - 1) < 0\end{array} \right.\) \( \Leftrightarrow \left\{ \begin{array}{l}m > \dfrac{1}{2}\\ - {m^2} + 5m - 2 < 0\end{array} \right.\) \( \Leftrightarrow \left\{ \begin{array}{l}m > 0,5\\\left[ \begin{array}{l}m > \dfrac{{5 + \sqrt {17} }}{2}\\m < \dfrac{{5 - \sqrt {17} }}{2}\end{array} \right.\end{array} \right.\) \( \Leftrightarrow m > \dfrac{{5 + \sqrt {17} }}{2}\)
b) \(\left\{ \begin{array}{l}{m^2} - m - 2 > 0\\{(2m - 1)^2} - 4({m^2} - m - 2) \le 0\end{array} \right.\) \( \Leftrightarrow \left\{ \begin{array}{l} - 1 < m < 2\\9 \le 0\end{array} \right.\). Hệ vô nghiệm.
