Another way to think about it is what is the slope of the secant line between those two points? And that would be our best estimate for the slope of the tangent line at x equals four. Do we know that it's a good estimate? Do we know that it's even close? No, we don't know for sure, but that would be the best estimate. It would be better than trying to take the average rate of change between when x equals three and x equals six, or between when x equals zero and x equals nine. These are pretty close around four.