Answer by JKismyhusbandbae: So this is really simple. You are probably making this out harder than it needs to be. Consider the set of ordered pairs {(-1,0), (4,-5), (6,-6), (9,11), (10,14)}. This set of ordered pairs is a function because for each value of x there is one and only one y-value. This means that the x value never repeats. Therefore any function is a function when the x value never repeats.
Looking at the table we want to find all it's ordered pairs: (0,4), (1,2), (2,3), (3,9), (4,1).
F(2) is 3 so when x equals 2.
So the ordered pair is (2,3) 2 is the x value and the f(2) is 3.