\(\large{(-8)^{-\frac{2}{3}}} = \frac{1}{\sqrt[3]{(-8)^2}} = \frac{1}{\sqrt[3]{64}} = \frac{1}{4} \)
\(\large{ 2^{-\frac{1}{2}}} = \frac{1}{\sqrt{2}} = \frac{\sqrt{2}}{\sqrt{2}\ \cdot \sqrt{2}} = \frac{\sqrt{2}}{\sqrt{4}} = \frac{\sqrt{2}}{2} = \frac{1}{2}\ \cdot \sqrt{2} \)
Dementsprechend dann:
\(\large{\frac{1}{4}\ \cdot \frac{1}{2}\ \cdot \sqrt{2}} = \frac{1}{8}\ \cdot \sqrt{2} \)