Question

Answer 1

Chọn B

Answer 2

\(2sinx+1=0\Leftrightarrow sinx=-\dfrac{1}{2}\)

\(\Rightarrow\left[{}\begin{matrix}x=-\dfrac{\pi}{6}+k2\pi\\x=\dfrac{7\pi}{6}+k2\pi\end{matrix}\right.\)