And we could just plug in a value, we could, let's try negative one. Negative one is pretty straightforward to evaluate. So let's see, you have four, you're gonna have four times negative one to the third power so that's gonna be four times negative one, minus five times negative one to the fourth power. So that's just gonna be one. So let's see, this is going to be negative four minus five, which is negative nine. So right over here, g prime is equal to negative nine. 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.