Ko ghi lại đề nha !
\(\Leftrightarrow sin\left(2x\right)=-\frac{1}{2}\)
\(\Leftrightarrow sin\left(2x\right)=sin\left(-\frac{pi}{6}\right)\)
\(\Leftrightarrow\orbr{\begin{cases}2x=-\frac{pi}{6}+k2pi\\2x=pi-\left(-\frac{pi}{6}\right)+k2pi\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=-\frac{pi}{12}+kpi\\x=\frac{7}{12}pi+kpi\end{cases}}\)


