1. [10 pts] Show that each of the following functions is not a bijection by giving either an element of the codomain that is not in the range, or • two elements of the domain that map to the same element in the range. Be sure to explain why each one is not a bijection! (a) a : N → N given by a(x) = 5x (b) b: N→ N given by b(x) = x + 5 6 if x = 1 (c) c: [1.6] → [2..6] given by c(x) = |r otherwise x +1 if a is even (d) d: Z→ Z given by d(x) if x is odd