[tex] log_{a}(b) = 5 \: \: \: \: < = > \: a {}^{5} = b \\ log_{a}( \sqrt[]{a b} ) = log_{a}( \sqrt{a \times {a}^{5}} ) = log_{a}( \sqrt{a {}^{6} } ) = \\ = log_{a}(a {}^{3} ) = 3 [/tex]