$$x = 2 - \frac{2}{2-\frac{1}{2}} = 2 - \frac{2}{\frac{4-1}{2}} = 2 - \frac{2}{\frac{3}{2}} = 2 - 2 \cdot \frac{2}{3} = 2 - \frac{4}{3} = \frac{6-4}{3} = \frac{2}{3}$$
$$x^{-1} = \frac{1}{x} = \frac{1}{\frac{2}{3}} = \frac{3}{2}$$
$$x - x^{-1} = \frac{2}{3} - \frac{3}{2} = \frac{4-9}{6} = -\frac{5}{6}$$
Ответ: $$-\frac{5}{6}$$