What is f of zero? So to evaluate f of zero, let's take the antiderivative of f prime of x, and then we're going to have a constant of integration there, so we can use the information that they gave us up here, that f of seven is equal to this. This might look like an expression, well it is an expression, but it's really just a number. 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.