Change
of Base Formula
A formula that allows you to rewrite a logarithm in terms of logs written with another base. This is especially
helpful when using a calculator to evaluate a log to any base other
than 10 or e.
Assume that x, a, and b are all positive. Also assume that a ≠ 1, b ≠ 1.
Change of base formula:
Example 1:
Example 2: (note that )
Example 3: 
See
also
Logarithm rules, common
logarithm, natural logarithm
