We know the second derivative here. But what they're asking us to do is without knowing what the function actually looks like, the function might look something like this. Let me just draw something. So the function might look, might look something like this. We're trying to figure out what f of 1.9 is. So if x is 1.9, f of 1.9, if that's the way the function actually looked, might be this value right over here. But we don't know for sure because we don't know much more about the function.