Piecewise Functions

I'd do it with Desmos Graphing calculator

 

Here is one I did as an example.  You have to add the open and closed circles seperataly I think.

 

https://www.desmos.com/calculator/lbfa84gy6b

 

Here is a tutorial if you want to know more:

https://www.youtube.com/watch?v=DCqClK1OQ-M