Question

Answer 1

92.

\(2sinx-1=0\)

\(\Leftrightarrow sinx=\dfrac{1}{2}\)

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

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{\pi}{6}+k2\pi\\x=\dfrac{5\pi}{6}+k2\pi\end{matrix}\right.\)

Answer 2

93.

\(sin\left(\dfrac{2}{3}x-\dfrac{\pi}{3}\right)=0\)

\(\Leftrightarrow\dfrac{2}{3}x-\dfrac{\pi}{3}=k\pi\)

\(\Leftrightarrow x=\dfrac{\pi}{2}+\dfrac{k3\pi}{2}\)

\(\Rightarrow\) có 4 điểm biểu diễn vị trí nghiệm