And so we know over this whole interval, since it's to the left of this critical point, we know that g prime of x is less than zero. And so our function itself is decreasing over this interval. And so we know we need to go from increasing to decreasing. So you can already say, well we can't go from increasing to decreasing at this critical point because we're already decreasing to the left of it. But anyway, let's just think about what's happening in the other intervals. So in the interval between zero and 4 5ths, so that interval right over there, so it's between zero and 4 5ths. Well let's just sample a number there.