/sci/ - Science & Math

Yo guys so I'm a tutor and I wanna know how best to represent the one-point-set part of the range of this function for a high school student.

So we have this piecewise function right, and I know the range is {-5}∪(-4,∞)
But that's how I would write it. I don't know how a highschooler would write {-5}. I asked and he doesn't know what {-5} is and has never seen it.

Would most teachers do it like (-5,-5)? Any ideas?