So if you look at this interval right over here, g prime is greater than zero, and then over the next interval, when you're decreasing, g prime would be less than zero. So what we really need to think about is when does g prime, so let me see, relative, we care about relative maximum point, and so that's essentially asking when does g prime go when does g prime go from positive to negative? From, I wrote frore, from g prime greater than zero to g prime less than zero. And the values that we could look at, or the points, are our critical points. And critical points are where g prime is either zero or it is undefined. So let's think about it. Where is g prime of x equal to zero?