\[\boxed{\mathbf{108}\mathbf{3}\mathbf{\text{.\ }}Еуроки\ - \ ДЗ\ без\ мороки}\]
\[3x - \frac{1}{x} = 8\]
\[\left( 3x - \frac{1}{x} \right)^{2} = 64\]
\[9x^{2} + \frac{1}{x^{2}} - 6 = 64\]
\[9x² + \frac{1}{x^{2}} = 70\]