1. $\dfrac{d}{dx}(5^x) = 5^x\ln\,5$ \gap[5] \t \\ 2. $\dfrac{d}{dx}(5e^x) = 5e^x$ \gap[5] \t Derivative of a constant times a function \\ 3. $\dfrac{d}{dx}\left[-4(20^x)\right] = -4(20^x)\ln\,20$ \gap[5] \t Derivative of a constant times a function \\ 4. $\dfrac{d}{dx}\left(x^2e^x\right) = 2xe^x + x^2e^x$ \gap[5] \t Product rule \\ $\qquad {}= e^x(2x+x^2)$