Curve sketching help (1 Viewer)

[Swailoi]

Does anyone know how and why my teacher divided up the curve into regions y=x and y=x-1?

Thanks in advance D

 

[fan96]

I've heard of something similar where you graph the numerator and denominator separately to make a "sign diagram" so you can tell which side of the y-axis the line will be. But that doesn't have anything to do with critical points.