But what about this magenta graph? It does have, it does look like it has the right trend. In fact, it intersects the x-axis at the right place, right over there. And at least over this interval, it seems it's positive from here to here. So it's positive. This graph is positive when the slope of the tangent line here is positive, and this graph is negative when the slope of the tangent line here is negative. Now one thing that might be causing some unease to immediately say that this last graph is the derivative of the first one is we're not used to situations where the derivative has more extreme points, more minima and maxima, than the original function.