This would be the point X comma F of X. And then this is the point C comma F of C right over here. So this is C comma F of C. So if you find the left-sided limit right over here, you're essentially saying, okay, let's find this slope. And then let me get a little bit closer. And let's get X a little bit closer, and then let's find this slope. And then let's get X even closer than that and find this slope. And in all of those cases, it would be zero.