math
posted by michele .
If A = {a, b, c, d} and B = {1, 0, 1} which of the following relations is a function from A to B.
a.(i) {(a, 0), (c, 1), (d, 1)}
b.(ii) {(a, 1), (b, 1), (c, 0), (d, 1)}
c.(iii) {(a, 1), (b, 1), (c, 0), (d, O)}
d.(iv) ({a, 1), (b, 0), (c, 1), (o.O), (a, 1)}
answer choice are
a.(i) and (iv)
b.(i) and (iii)
c.(ii) and Oii)
d.(iii) and (iv)
V

i is a one to one mapping, but all do not map. Where does b map to?
ii is a one to one, each abcd maps to a unique map
iii each a,b,c, d maps to a particular choice.
iv how can (a) map to 1 and 1 and be a function? It cant.
so ii, iii are functions. check my logic.
So,