Or a function could look something like this. It could look something like that. And then the absolute maximum could occur at the end point of the interval, or the other possibility is that the function looks something like this, at which point the maximum would be at this critical point. And I say critical point as opposed to just a point where the slope is zero, because it's possible that the function is not differentiable there. You could imagine a function that looks like this. And maybe it wouldn't be differentiable there, but that point there still would be the absolute maximum. So what we really just have to do is evaluate g at the different end points of this interval to see how high it gets or how large of a value we get for the g at the end points.