Well, it sure looks like the slope of the tangent line is about 1 1⁄2. We could try, what happens when e to the x is equal to five? Well, the slope of the tangent line here sure does look pretty close, sure does look pretty close to five. And so, just eyeballing it, is it the case that the slope of the tangent line of e to the x is the same thing, is e to the x? And I will tell you, and this is an amazing thing, that that is indeed true. That if I have some function, f of x, that is equal to e to the x, and if I were to take the derivative of this, this is going to be equal to e to the x as well. Or another way of saying it, the derivative with respect to x of e to the x is equal to e to the x.