There's no variables in this. And so we can use that to solve for our constant of integration, and then we will have fully known what f of x is, and we can use that to evaluate f of zero. So let's just do it. So if f prime of x is equal to 5e to the x, then f of x is going to be equal to the antiderivative of f prime of x, so the antiderivative of 5e to the x, dx. And this is the thing that I always find amazing about exponentials, and actually let me just take a step. I'll take that five out of the integral so it becomes a little bit more obvious. And so the antiderivative of e to the x, well that's just e to the x, because the derivative of e to the x is e to the x, which I find amazing every time I have to manipulate or take the derivative or antiderivative of e to the x.