Algebraic Rules and Graphing Rules for Working with Logarithms
The rules for working with logarithms are relatively straight-
forward and follow from the definition of the logarithmic
function. The rules for logarithmic operations that you need to
be familiar with are as follows: b) = Log(a) + Log(b) Log(a ÷ b
) = Log(a) - Log(b) Log(a) + Log(b) = Log(a) + Log(b) ; not much
you can do with this! Log(a) - Log(b) = Log(a) - Log(b) ; you
can't do much here either! Log(ab) = b × Log(a) Though these
rules are not proven here they follow rather simply from the
definition of logarithms. To save space we won't bother with the
proofs. For one thing you can test out these rules on your
calculator to check and convince yourself. For instance, try the
following: Log(2 × 3) = Log(2) + Log(3) ?? Is this true? × 3) =
Log(6) = 0.77815, so this is the numerical value for the left
hand side. Now, Log(2) = 0.30103 and Log(3) = 0.47712, for the
right hand side. Adding the values for the right hand side
together we get: Log(2) + L