a/ \(\Leftrightarrow\left[{}\begin{matrix}sinx=0\\sinx-2=0\left(vn\right)\end{matrix}\right.\) (vô nghiệm do \(sinx\le1\) ; \(\forall x\))
\(\Leftrightarrow x=k\pi\)
b/ \(\Leftrightarrow\left[{}\begin{matrix}2sinx-3=0\\2sinx-\sqrt{2}=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}sinx=\frac{3}{2}\left(vn\right)\\sinx=\frac{\sqrt{2}}{2}=sin\frac{\pi}{4}\end{matrix}\right.\) (lý do vô nghiệm như câu a)
\(\Rightarrow\left[{}\begin{matrix}sinx=\frac{\pi}{4}+k2\pi\\sinx=\frac{3\pi}{4}+k2\pi\end{matrix}\right.\)
c/ ĐKXĐ: \(sinx\ne-\frac{1}{2}\)
\(\Leftrightarrow2sinx-1=6sinx+3\)
\(\Leftrightarrow4sinx=-4\Rightarrow sinx=-1\)
\(\Rightarrow x=-\frac{\pi}{2}+k2\pi\)
d/ \(\Leftrightarrow2=3-sinx\)
\(\Leftrightarrow sinx=1\Rightarrow x=\frac{\pi}{2}+k2\pi\)
(các câu \(k\in Z\) )
