Mantra: A Logarithm is an Exponent
“Log base b of y is x”
If the base is not given, assume 10
Natural Log: “l” “n” of “y” is “x”
Logs to the base "e" (2.71828...), a transcendental number, are called natural logs and are written as ln.
Since logarithms are nothing more than exponents, these rules come from the rules of exponents:
Where a, b, x and y are real numbers not equal to zero.
Since e and ln were created to have special calculus properties we often want to change base to e.
Example 1
Example 2