So let's think about what needs to, we don't have a graph of f in front of us. So let's think about what needs to be true for f to have a relative maximum at a point. So let's, we are probably familiar with what relative maxima look like. They look like a little lump like that. They could also actually look like that, but since this is a differentiable function over the interval, we're probably not dealing with a relative maximum that looks like that. And so what do we know about a relative maximum point? So let's say, let's say that's our relative maximum.