Fundamental properties of logarithms (Grant's
tomb properties):
logbbx
= x
bxlogbx
= x
A logarithmic equation is an equation for
which there is a logarithm on one or both sides.
The key to solving logarithmic equations is the log
of both sides theorem: If A, B, and
b are positive real numbers (with b not
equal to 1), then
logbA = logbB
is equivalent to A = B.
If A, B, and b are positive numbers,
p is any real numbers and b is not equal
to 1:
First law (Addition): logb(AB)
= logbA + logbB
Second law (Subtractive): logb(A/B)
= logbA - logbB
Third law (Multiplicative): logbAp
= p logbA