Tìm txđ hàm số: y=tan(3x+6π/7)

\[\begin{array}{l} y = \tan \left( {3x + \frac{{6\pi }}{7}} \right)\\ DK:\,\,\cos \left( {3x + \frac{{6\pi }}{7}} \right) \ne 0\\ \Leftrightarrow 3x + \frac{{6\pi }}{7} \ne \frac{\pi }{2} + k\pi \\ \Leftrightarrow 3x \ne - \frac{{5\pi }}{{14}} + k\pi \\ \Leftrightarrow x \ne - \frac{{5\pi }}{{42}} + \frac{{k\pi }}{3}\,\,\,\left( {k \in Z} \right)\\ \Rightarrow TXD:\,\,\,D = R\backslash \left\{ { - \frac{{5\pi }}{{42}} + \frac{{k\pi }}{3}\,\,\,\left( {k \in Z} \right)} \right\} \end{array}\]