I'm using a lot of vice versa here. So now let's, and I wanted to think of it in terms of F prime because we have the graph of F prime. So F prime goes from increasing to decreasing, or vice versa, or we could go from decreasing to increasing. Well let's think about it. Let's see, over here, F prime is, F prime is decreasing, decreasing, decreasing, decreasing, and then it increases. So we have a point of inflection right over here, right when F prime of x is zero. So, and that's because F prime is differentiable, so the derivative is definitely, the derivative is zero right at that point of inflection right over here, so if that happens at x equals negative one and over here, then F prime starts increasing, but then it, right at x equals one, then it starts decreasing.