1 câu trả lời
\((\cos 2x +1)(2\sin x -3)=0\) \(\Rightarrow\left\{ \begin{array}{l} \cos 2x+1=0 \\ 2\sin x -3 \end{array} \right .\Rightarrow \left\{ \begin{array}{l} \cos 2x=-1 \\ \sin x =\dfrac{3}{2}(>1)\text{ (loại)} \end{array} \right .\) \(\Rightarrow 2x=\pi+k2\pi,(k\in\mathbb Z)\) \(\Rightarrow x=\dfrac{\pi}{2}+k\pi,(k\in\mathbb Z)\).
