HP Prime whats in the printing can be done.

[Didier Lachieze]

I don't have problems entering the equations in the Prime but the values of F1(X) and F2(X) in the Plot view are NaN.

Here is how I would do it without the 'where' operator:

       

You can also use the function PIECEWISE (see the on-calc help for more details):

   

Note: in Textbook mode you can avoid specifying the second condition.