[SOLVED] "Determine if ___ is a function" 1. The problem statement, all variables and given/known data Determine whether f is a function from Z to R if a) f(n) = ±n. b) f(n) = Sqrt(n^2 + 1). c) f(n) = 1 / (n^2 – 4). 3. The attempt at a solution Have the book right in front of me, and reading the definitions of functions, transitions, and maps, but nothing's registering in my brain. To me, ±n would not be a function because it would be the same as the equation x = y^2. However, this whole "Z to R" business has me lost. I know what Z and R represent, but I don't see how that has any meaning on whether or not f(n) is a function. What is a function? More importantly, what makes something not a function? Haven't attempted b) or c), as they look even worse. Trying to comprehend the concept of a) first.