Đáp án:
`\(\left[ \begin{array}{l}x=\dfrac{\pi}{6}-k2\pi\\x=\dfrac{\pi}{18}+\dfrac{k2\pi}{3}\end{array} \right.\)`(kinZZ)`
Giải thích các bước giải:
`cos(2x-pi/6)=cosx`
`<=>`\(\left[ \begin{array}{l}x=2x-\dfrac{\pi}{6}+k2\pi\\x=-(2x-\dfrac{\pi}{6})+k2\pi\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}-x=-\dfrac{\pi}{6}+k2\pi\\3x=\dfrac{\pi}{6}+k2\pi\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=\dfrac{\pi}{6}-k2\pi\\x=\dfrac{\pi}{18}+\dfrac{k2\pi}{3}\end{array} \right.\)`(kinZZ)`
