Exponential and Logarithmic Differentiation
Exponential Functions to Base a
If a is a positive real number (a does not = 1) and x is any real number, then the exponential function to the base a is denoted by ax and is defined as x = e(ln a)x.
If a = 1, then y = 1x = 1 is a constant function.
Logarithmic Functions to Base a
If a is a positive real number (a does not = 1) and x is any real number, then the logarithmic function to the base a is denoted by logax and is defined as logax = (1/ln a) ln x
Derivatives for Bases other than e
Let a be a positive real number (a does not = 1) and let u be a differentiable function of x.
d/dx[ax] = (lna)ax
d/dx[au] = (ln a)au du/dx
d/dx[lobax] = 1/((ln a)x)
d/dx[logau] = 1/((ln a)u) du/dx
The Power Rule for Real Exponents
Let n be any real number and let be a differentiable function of x.
d/dx[xn] = nxn-1
d/dx[un] = nun-1 du/dx
Derivative of the Natural Logarithmic Function
Let u be a differentiable function of x.
1. d/dx[ln x] = 1/x, x > 0
But don't forget the Chain rule!
2. d/dx[ln u] = u'/u, u > 0

