ĐK: \(x\ne\dfrac{\pi}{15}+\dfrac{k\pi}{3}\)
\(cot\left(3x-\dfrac{\pi}{5}\right)+tan\dfrac{2\pi}{5}=0\)
\(\Leftrightarrow tan\left(\dfrac{7\pi}{10}-3x\right)+tan\dfrac{2\pi}{5}=0\)
\(\Leftrightarrow tan\dfrac{2\pi}{5}=tan\left(3x-\dfrac{7\pi}{10}\right)\)
\(\Leftrightarrow\dfrac{2\pi}{5}=3x-\dfrac{7\pi}{10}+k\pi\)
\(\Leftrightarrow x=\dfrac{11\pi}{30}-\dfrac{k\pi}{3}\left(tm\right)\)