In either of these two situations, just to make sure you understand what you're looking at, this is a situation where if you just tried to evaluate this limit right here, you're going to get f of c, which is 0, or the limit as x approaches c of f of x over the limit as x approaches c of g of x, and that's going to give you 0 over 0. You say, hey, I don't know what that limit is, but this says, well, look, if this limit exists, I could take the derivative of each of these functions and then try to evaluate that limit. If I get a number, if that exists, then they're going to be the same limit. This is a situation where when we take the limit, we get infinity over infinity, or negative infinity, or positive infinity over positive or negative infinity. These are the two indeterminate forms. To make it all clear, let me just show you an example, because I think this will make things a lot more clear. Let's say we are trying to find the limit.