ly express whether a function is onto or one to one.
For each of the functions below, indicate whether the function is onto, one-to-one, neither or both. If the function is not onto or not one-to-one, give an example showing why.
f: Z × Z → Z × Z, f(x, y) = (1-y, 1-x)
f: Z+ × Z+ → Z+, f(x, y) = 2x + y.