So I can treat it like a constant. So this is going to be the same thing as saying the limit as x approaches c of u of x minus u of c is equal to zero. And actually, in the video where we prove that differentiability implies continuity, we started with this, and we proved that right over there. We showed that these two are equivalent things. But hopefully you can even think about the intuition. This is just, if the limit as u of x approaches, the limit of u of x as x approaches c is equal to this, then when you evaluate this limit, the limit as x approaches c, well, this thing is going to approach u of c, because we saw it right up here. u of c minus u of c is indeed going to be equal to zero.