In computer science, methods (a.k.a. functions) often take more than one input. In the case where a function takes two inputs, we can think of the input (mathematically) as an ordered pair. Consider the following functions from

Z Z to Z.Is each function one-to-one? Is each onto? If the answer is no, you must provide a specific counterexample.

(a) f(x, y) = x^2 y^2.

(b) f(x, y) = |x| |y|.

(c) f(x, y) = x + y 2.