Is (-4,1), (1,-8), (1,-2) a function?
These values do not represent a function.
A function is defined as a relation for which each value from the set the first components of the ordered pairs is associated with exactly one value from the set of second components of the ordered pair.
Here, in your example, the x-value 1 is plugged into the equation and receives two different y-values (both-8 and -2). therefore, this is not a function.