Đáp án:
\(x \ne k\pi \)
Giải thích các bước giải:
\(\begin{array}{l}
DK:\left\{ \begin{array}{l}
5 - 3\cos 2x \ge 0\\
1 + \sin \left( {2x - \dfrac{\pi }{2}} \right) \ne 0
\end{array} \right.\\
\to \left\{ \begin{array}{l}
\dfrac{5}{3} \ge \cos 2x\left( {ld} \right)\\
\sin \left( {2x - \dfrac{\pi }{2}} \right) \ne - 1
\end{array} \right.\\
\to 2x - \dfrac{\pi }{2} \ne - \dfrac{\pi }{2} + k2\pi \\
\to 2x \ne k2\pi \\
\to x \ne k\pi \left( {k \in Z} \right)
\end{array}\)
