4. (a) Consider the function f : Z Z Z where f(m, n) = 2m-n. Is this function onto? (b) Consider the function f : Z x Z Z where f(m, n) = m2-n2. Is this function onto? (c) Define the set Cthe set of all residents of Colorado. Define in words a function f:C-Z I your function one-to-oe? Is it onto? Be sure that the f you defined is indeed a function. Be creative and have fun! (d) Again, define the set C- the set of all residents of Colorado. Define in words a functionf CZ. However this time, make sure that your function is one-to-one. (Make sure to give a different example from part (c))