Stage: 5 Challenge Level:
Why do this problem?
It requires an understanding of how to handle functions that are
defined differently on different parts of their domains and how to
interpret the situation when the derivative takes different values
close to point but on opposite sides of the point.
A short problem that can be used as a lesson starter.
What can you say about the function when $x< 0$?
What can you say about the function when $x> 0$?