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Start by using two auxiliary logarithmic expressions. Then rewrite them in exponential form and apply the Properties of Exponents. Finally, go back to logarithmic expressions after simplifying.
See solution.
To derive the Properties of Logarithms, we can start by defining two auxiliary general logarithmic expressions.
a = log_b m c = log_b n
Now, from the definition of logarithm we know that there is an equivalent exponential representation for a logarithmic expression.
y= b^x ⇔ x = log_b y
We can use this to rewrite our auxiliary logarithmic expressions in exponential form.
Using the expressions introduced before, lets find the product of m and n.
a^m*a^n=a^(m+n)
Rewrite mn = b^(a+c) as log_b(mn) = a+c
a= log_b m, c= log_b n
This last result is known as the Product Property of Logarithms.
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log_b(mn) = log_b m + log_b n |
Using the expressions introduced above, we will now find the quotient of m and n.
a^m/a^n= a^(m-n)
Rewrite m/n = b^(a-c) as log_b(m/n) = a-c
a= log_b m, c= log_b n
This last result is known as the Quotient Property of Logarithms.
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log_b(m/n) = log_b m - log_b n |
Let's consider the logarithm base b of m^n. Since we know that m = b^a, we can use it in our expression.
(a^m)^n=a^(m* n)
log_b(b^m)=m
a= log_b m
Multiply
This last result is known as the Power Property of Logarithms.
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log_b(m^n) = nlog_b m |