\[\frac{(3x - 1)^{2} - 6x + 6}{x} =\]
\[= \frac{9x^{2} - 6x + 1 - 6x + 6}{x} =\]
\[= \frac{9x^{2} - 12x + 7}{x} = \frac{9x^{2}}{x} - \frac{12x}{x} + \frac{7}{x} =\]
\[= 9x - 12 + \frac{7}{x}\ \ \in Z\ при:x = \pm 1;\ \ x = \pm 7.\ \]