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. So this is going to be 5e to the x plus c. And you can verify, take the derivative of 5e to the x plus c. The derivative of 5e to the x, well that's 5e to the x, so that works out, and the derivative of c is zero, so you wouldn't see it over here. So now let's use this information to figure out what c is so that we know exactly what f of x is, and then we can evaluate f of zero. So we know that f of seven, so when x is equal to seven, we're going to, this expression is going to evaluate to this thing, 40 plus 5e to the seven. So five times e to the seventh power plus c is equal to 40, is equal to 40 plus 5e to the seventh power. And notice all I did is said okay, f of seven. Well if this is f of x, f of, let me write this down.