\[3x^{2} - (3k - 1)x - k = 0\]
\[D = (3k - 1)^{2} - 4 \cdot 3 \cdot ( - k) =\]
\[= 9k^{2} - 12k + 1 + 12k =\]
\[= 9k^{2} + 1 > 0\]
\[x_{1} = \frac{3k - 1 + \sqrt{9k^{2} + 1}}{6}\]
\[x_{2} = \frac{3k - 1 - \sqrt{9k^{2} + 1}}{6}\]
\[Ответ:\ x = \frac{3k - 1 \pm \sqrt{9k^{2} + 1}}{6}.\]