Highlight an interval where f prime of x is greater than zero. So same thing, where our function is increasing, but it's increasing at a slower and slower rate. So our function is increasing. So our function is increasing in this whole region right over here. And we see it's really steep here. Then it's getting less steep and less steep. And it's getting closer and closer to zero, the slope of the tangent line or the rate of increase of the function.