Differentiation Rules

Exponential function:
* \frac{d}{dx} a^{u} = a^{u} \ln (a) \frac{d}{dx}u
* \frac{d}{dx} a^{x} = a^{x} \ln (a) 
* \frac{d}{dx} \mathrm{e}^{u} = \mathrm{e}^{u} \frac{d}{dx}u
* \frac{d}{dx} \mathrm{e}^{x} = \mathrm{e}^{x}