This point at which we transition from being concave downwards to concave upwards, or the point at which our derivative has an extremum point, or the point at which our second derivative switches signs like this, we call it an inflection point. And the most typical way that people think about how could you test for an inflection point, it's a point, well, conceptually, it's where you go from being a downward opening u to an upward opening u, or when you go from being concave downwards to concave upwards. But the easiest test is it's a point at which your second derivative switches signs. So in this case, we went from negative to positive, but we could have also switched from being positive to negative. So inflection point, your second derivative, f prime prime of x, switches signs, goes from being positive to negative or negative to positive, switches signs. So this is a case where we went from concave downwards to concave upwards. If we went from concave upwards to concave downwards like that, then at this inflection point, up until that point, the slope was increasing.