## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$\log _{a}(M N)=\log _{a} M+\log _{a} N$
Recall the product rule for logarithms: $$\log _{a}(AB)=\log _{a} A+\log _{a} B$$ Thus, $$\log_a{MN}=\log_a{M}+\log_a{N}$$