The slope of the line that connects these points is one. The slope of the line that connects these points is one. So the limit of this expression, or I would say the value of this expression, is approaching two different values as X approaches C from the left or the right. From the left, it's approaching negative one, or it's constantly negative one, and so it's approaching negative one, you could say. And from the right, it's one, and it's approaching one the entire time. And so we know if you're approaching two different values from on the left-sided or the right-sided limit, then this limit will not exist. So here, this is not differentiable.