The order can be in a few different ways like 213, 321, 132, 312. You get the idea
I mean they both have a factor of 3 you just take -3x > 9 and just flip it
A) Who would not love birdies??
In order to be differentiable everywhere, 
must first be continuous everywhere, which means the limits from either side as 
must be the same and equal to 
. By definition, 
, and
so we need to have 
.
For to be differentiable at 
, the derivative needs to be continuous at , i.e.
We then need to have
Then
