Last, we were after something that was happening at x=1x=1x = 1 and we couldn’t actually plug x=1x=1x = 1 into our formula for the slope. Despite this limitation we were able to determine some information about what was happening at x=1x=1x = 1 simply by looking at what was happening around x=1x=1x = 1. This is more important than you might at first realize and we will be discussing this point in detail in later sections.

Likewise, at the second point shown, the line does just touch the graph at that point, but it is not “parallel” to the graph at that point and so it’s not a tangent line to the graph at that point.

We will be seeing limits in a variety of places once we move out of this chapter.