[tex]\displaystyle \left(\begin{}{- \frac{1}{2} }&&\\&&\\&&\end{.}\right) ^4 \cdot \left(\begin{}{ \frac{1}{2} }&&\\&&\\&&\end{.}\right)^3 \cdot \left(\begin{}{- \frac{1}{2} }&&\\&&\\&&\end{.}\right) ^{-6} = \frac{1}{16} \cdot \frac{1}{8} \cdot 64= \frac{1}{128} \cdot 64= \frac{64}{128} = \frac{1}{2} [/tex]
