It's fine. It is a function. The language can be very convoluted. Put simply a domain value cannot have 2 different range values.
Step-by-step explanation:
The confusing part I think, is probably the fact that -1 and 1 both have an answer of 5.
That's fine. Parabolas do that and they are functions. Two different xs can have the same value. The thing that eliminates functions is when the x value (the domain) has two different y values (the range values). Then you don't have a function.
To try and make it clearer if 1 pointed at both 3 and 5 you would not have a function.
Step-by-step explanation: all horizontal lines are of the form "y = some number", and the equation "y = some number" always graphs as a horizontal line.
