\[\left( \frac{x - 2}{x + 2} + \frac{x + 2}{x - 2} \right)\ :\frac{x^{2} + 4}{x^{2} - 4} =\]
\[= \frac{(x - 2)^{2} + (x + 2)^{2}}{(x + 2)(x - 2)}\ :\frac{x^{2} + 4}{x^{2} - 4} =\]
\[= \frac{2x^{2} + 8}{x^{2} - 4}\ :\frac{x^{2} + 4}{x^{2} - 4} =\]