I am reading the book "An Abundance Of Katherines" by John Green. There is a lot of math stuff in it which I am unable to comprehend. Somebody help me out in this regard.
Here the protagonist, Colin Singleton, is trying to plot Dumpers and Dumpees in a relationship in the form of a graph. I am not able to understand what the author is trying to say. Please tell me what is the use of a differential(How do we obtain the differential?) in this graph. And I would like to know how the graph is plotted. I am not able to comprehend how the protagonist is trying to plot himself on the graph. How is he getting -4 as the differential? Please explain to me in detail if possible.
The part of the book that I am not able to understand.
Kindly help me, and thanks in advance.