ECONS 391 Midterm: ECON 207 Western Washington Midterm 1 Answer Key
Document Summary
1. (a) let a and b be nonempty sets. Let f : a b be a function. State the de nitions of: an injection (one-to-one function), a surjection (onto function) and a bijection. Formal de nitions must include quanti ers either in english sentences or logical statements. (b) consider the function de ned by g(n) = (cid:22)4 n. 3 (cid:23) + 1 for all n z. Recall that the golden ratio is a positive solution of the equation 2 = + 1. In this problem we study devisability by 5. Recall that when divided by 5 an integer leaves a remainder.
