When x=2, shouldn't f(x) equals 2 as well?
This chart says when x=2, f(x)=3, when x=3, f(x)=5, when x=7, f(x)=6, and so on.
What does it mean?
if all you have are those three pairs, it's possible to have lots of functions that fit.
Why do you think f(2) = 2, when the table says f(2)=3?
There must be more to the problem than you have said.