# Find the Derivative – d/db log base b of 18

Rewrite using the change of base formula.
The change of base rule can be used if and are greater than 0 and not equal to 1, and is greater than 0.
Substitute in values for the variables in the change of base formula, using .
Differentiate using the Constant Multiple Rule.
Since is constant with respect to , the derivative of with respect to is .
Rewrite as .
Differentiate using the chain rule, which states that is where and .
To apply the Chain Rule, set as .
Differentiate using the Power Rule which states that is where .
Replace all occurrences of with .
Simplify the expression.
Move to the left of .
Rewrite as .
The derivative of with respect to is .
Combine fractions.
Combine and .
Combine and .
Move to the denominator using the negative exponent rule .
Find the Derivative – d/db log base b of 18