a) \(\sqrt[12]{a^{3}} = a^{\frac{3}{12}} = a^{\frac{1}{4}} = \sqrt[4]{a}\)
б) \(\sqrt[18]{a^{12}} = a^{\frac{12}{18}} = a^{\frac{2}{3}} = \sqrt[3]{a^{2}}
\)
в) \(\sqrt[8]{a^{18}} = a^{\frac{18}{8}} = a^{\frac{9}{4}} = a^{2 + \frac{1}{4}} = a^{2} \cdot a^{\frac{1}{4}} = a^{2} \sqrt[4]{a}\)