Xác định \(m\) để phương trình \(\left( {2m - 1} \right)\tan \dfrac{x}{2} + m = 0\) có nghiệm \(x \in \left( {\dfrac{\pi }{2};\pi } \right)\).
A.\( - 1 < m < \dfrac{1}{4}\)
B.\(\left[ \begin{array}{l}m < - \dfrac{1}{2}\\m > 1\end{array} \right.\)
C.\(\left[ \begin{array}{l}m > 0\\m < - 1\end{array} \right.\)
D.\(\dfrac{1}{3} < m < \dfrac{1}{2}\)
A.\( - 1 < m < \dfrac{1}{4}\)
B.\(\left[ \begin{array}{l}m < - \dfrac{1}{2}\\m > 1\end{array} \right.\)
C.\(\left[ \begin{array}{l}m > 0\\m < - 1\end{array} \right.\)
D.\(\dfrac{1}{3} < m < \dfrac{1}{2}\)
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Hóa Học lớp 12
