\[\boxed{\text{390\ (390).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[\textbf{а)}\ a^{4} = \left( a^{2} \right)^{2}\]
\[\textbf{б)}\ a^{6} = \left( a^{3} \right)^{2}\]
\[\textbf{в)}\ a^{18} = \left( a^{9} \right)^{2}\]
\[\textbf{г)}\ \frac{1}{a^{10}} = \left( \frac{1}{a^{5}} \right)^{2}\]
\[\textbf{д)}\ a^{2}b^{8} = \left( ab^{4} \right)^{2}\]
\[\textbf{е)}\ \frac{a^{6}}{b^{12}} = \left( \frac{a^{3}}{b^{6}} \right)^{2}\ \]