Yes, in other words what is Z exactly.
Your current answer makes sense but how should I state it more accurately. I mean what your wrote is not wrong but it would be the same as saying that the image of g, where g : R -> R, g(x) = x2 - 4x + 1, is {x2 - 4x + 1 : x in R} instead of [-3, +infinity)
So on my first course of Algebra in university I have been asked to find the image of the following function:
f : Z x Z -> Z, f(x, y) = x2 - y2
In high school I worked only with single variable functions and I could have found the image by drawing its graph, using limits or using some specific...