Let me just add another color. We see that our function is decreasing right over here. So f decreasing, decreasing, which means that f-prime of x needs to be less than zero. So our relative maximum point should be, should happen at an x-value. It should happen at an x-value where our first derivative transitions from being greater than zero to being less than zero. So what x-values, let me say this. So we have f has relative, let me just write it shorthand, relative maximum at x-values where f-prime transitions, transitions, transitions from positive, positive, to negative, to, let me write this a little bit neater, to negative, to negative.