And to think about that, let's imagine this point right over here. So let's call this x sub 3. If we look at the tangent line right over here, if we look at the slope right over here, it looks like f prime of x sub 3 is equal to 0. So based on our definition of a critical point, x sub 3 would also be a critical point. But it does not appear to be a minimum or a maximum point. So a minimum or a maximum point, that's not an endpoint. It's definitely going to be a critical point.