All of those are the possible candidates for where f hits a maximum value. So first we could think about, well, actually, let's find the critical numbers first since we have to do it. So let's take the derivative of f. f prime of x is going to be equal to the derivative of natural log of x is 1 over x. So it's going to be 8 over x minus 2x. And let's set that equal to zero. So if we focus on this part right over here, we could add 2x to both sides, and we would get 8 over x is equal to 2x. Multiply both sides by x.