That's a strange question. I'm not sure what you mean by "represent"! f(5) is, of course, the value of the function f(x) at x= 5. I have feeling that you are supposed to say that f(5) is a local maximum for the function, but unless f is continuous, which is not given, that is not true. For example, take f(x)= x for x< 4, x- 4, for x>= 5. Then f(5)= 1 but there exist values of x, arbitrarily close to 5, such that f(x)> 1. For example, f(4.9)= 4.9>1.