y=cot (3x + pi/6))))))

`~rai~`

\(y=\cot\left(3x+\dfrac{\pi}{6}\right)\\ĐKXĐ:\sin\left(3x+\dfrac{\pi}{6}\right)\ne 0\\\Leftrightarrow 3x+\dfrac{\pi}{6}\ne k\pi\\\Leftrightarrow 3x\ne -\dfrac{\pi}{6}+k\pi\\\Leftrightarrow x\ne -\dfrac{\pi}{18}+k\dfrac{\pi}{3}.(k\in\mathbb{Z})\\TXĐ:D=\mathbb{R}\backslash\left\{-\dfrac{\pi}{18}+k\dfrac{\pi}{3}\Big|k\in\mathbb{Z}\right\}.\)