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 .

Since is constant with respect to , the derivative of with respect to is .

Rewrite as .

To apply the Chain Rule, set as .

Differentiate using the Power Rule which states that is where .

Replace all occurrences of with .

Move to the left of .

Rewrite as .

The derivative of with respect to is .

Combine and .

Combine and .

Move to the denominator using the negative exponent rule .

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