The function from the previous example {{MATH_74}} is a type of function that we call a {{CMD_75}}tower function{{CMD_76}}. Tower functions are functions written as {{MATH_77}}, an exponential where both the base and exponent depend on the variable. This logarithmic differentiation is one method of differentiating a tower function. However we can also write {{MATH_78}} By rewriting like this we can differentiate tower functions using chain rule and product rule. In the previous example, the derivative of {{MATH_79}} was calculated in both of these methods. Let's differentiate one more tower functions using both methods.