Find limit as h approaches 0 of $ \frac{e^{x(h+2)^2} - e^{4x}}{h} $
I know that somehow this is related to me taking the partial derivative of x
I also know $\frac{\partial f}{\partial x}(x,y) = \lim_{h\to0} \frac{f(x+h,y) - f(x,y)}{h}$
But I don't know what to do from here.