And then we talked about the interval over which the function is concave upwards. But we see here that there's a point at which we transition from being concave downwards to concave upwards. Before that point, the slope was decreasing, and then the slope starts increasing. The slope was decreasing, and then the slope started increasing. So that's one way to look at it. Right here in our function, we go from being concave downwards to concave upwards. When you look at our derivative at that point, our derivative went from decreasing to increasing.