Đáp án:
b) \(m \ge \dfrac{9}{4}\)
Giải thích các bước giải:
\(\begin{array}{l}
a)DK:\left\{ \begin{array}{l}
1 > 0\left( {ld} \right)\\
9{m^2} + 6m + 1 - 1.\dfrac{1}{4} < 0
\end{array} \right.\\
\to 9{m^2} + 6m < 0\\
\to 3m\left( {3m + 2} \right) < 0\\
\to - \dfrac{2}{3} < m < 0\\
b)DK:\left\{ \begin{array}{l}
- 1 < 0\left( {ld} \right)\\
4{m^2} - 4m + 1 - 4.\left( { - 1} \right)\left( { - {m^2} + 2} \right) \le 0
\end{array} \right.\\
\to 4{m^2} - 4m + 1 - 4{m^2} + 8 \le 0\\
\to - 4m + 9 \le 0\\
\to m \ge \dfrac{9}{4}
\end{array}\)
