All right, so she made a big conclusion here. She assumed that because the derivative was zero, that we have a relative extremum. So let's just see if you can even just make that conclusion. In order to have a relative extremum, your curve is gonna look something like this, and then you would have a relative extremum right over here. And over here, your slope goes from being positive, and then it hits zero, and then it goes to being negative. Or you could have a relative extremum like this. This would be a maximum point.