Domain not checked out, please see inside...

[Aries]

Ok, Stefan, let's suppose the Prime CAS "expands" the primary function f(x) in order to remove, as you said, the discontinuity, apart from the fact we have two different functions, now the question is, is there a way to keep the CAS from removing the "hole" and giving the wrong result ?
We have seen before that setting "simplify" to "None" is useless.