\[\frac{\sqrt{8 + \sqrt{10}}}{\sqrt{8 - \sqrt{10}}\ } + \frac{\sqrt{8 - \sqrt{10}}}{\sqrt{8 + \sqrt{10}}} =\]
\[= \frac{\sqrt{8 + \sqrt{10}} \cdot \sqrt{8 + \sqrt{10}} + \sqrt{8 - \sqrt{10}} \cdot \sqrt{8 - \sqrt{10}}\ }{\left( \sqrt{8 - \sqrt{10}} \right)\left( \sqrt{8 + \sqrt{10}} \right)} =\]
\[= \frac{8 + \sqrt{10} + 8 - \sqrt{10}}{\sqrt{\left( 8 - \sqrt{10} \right)\left( 8 + \sqrt{10} \right)}} =\]
\[= \frac{16}{\sqrt{64 - 10}} = \frac{16}{\sqrt{54}} =\]
\[= \frac{16\sqrt{54}}{54} = \frac{8\sqrt{54}}{27}.\]