[tex] log_{25}(50) - log_{2}(2) = log_{5 {}^{2} }(50) - 1 = \frac{1}{2} \times log_{5}(50) - 1 = \frac{1}{2} \times log_{5}(25 \times 2) - 1 = \frac{1}{2} \times (2 + log_{5}(2) ) - 1 = \frac{1}{2} \times log_{5}(2) [/tex]
[tex] log_{7}( \frac{5}{7} ) - log_{7}(5) = log_{7}( \frac{ \frac{5}{7} }{5} ) = log_{7}( \frac{1}{7} ) = log_{7}(7 {}^{ - 1} ) = - 1[/tex]
[tex] log_{9}( \frac{1}{81} ) = log_{3 {}^{2} }(3 {}^{ - 4} ) = - 2[/tex]
