\[a^{6} \cdot \left( a \cdot a^{2} \right)^{2} = \ *\ \cdot \left( - a^{4} \right)\]
\(\ a^{6} \cdot \left( a^{1 + 2} \right)^{2} = \ *\ \cdot ( - a^{4})\)
\[a^{6} \cdot \left( a^{3} \right)^{2} = \ *\ \cdot \left( - a^{4} \right)\]
\[a^{6} \cdot a^{6} = \ *\ \cdot \left( - a^{4} \right)\]
\[a^{6 + 6} = \ *\ \cdot \left( - a^{4} \right)\]
\[a^{12} = \ *\ \cdot \left( - a^{4} \right)\]
\[*\ = a^{12}\ :\left( - a^{4} \right)\]
\[*\ = - a^{12 - 4}\]
\[*\ = - a^{8}.\]