Now one question you might be wondering is, why are you learning this in a calculus class? Couldn't you have learned this in an algebra class? The answer is yes. But what's going to be interesting, and it's really one of the foundational ideas of calculus, is, well, what happens as these points get closer and closer together? We found the average rate of change between one and three, or the slope of the secant line from one comma one to three comma nine. But what instead if you found the slope of the secant line between two comma four and three comma nine? So what if you found this slope?