Question

Which sets of ordered pairs represent functions from A to B? Explain.

A = {a, b, c} and B = {0, 1, 2, 3}

A. {(a, 1), (c, 2), (c, 3), (b, 3)}
B. {(a, 1), (b, 2), (c, 3)}
C. {(1, a), (0, a), (2, c), (3, b)}
D. {(c, 0), (b, 0), (a, 3)}


I narrowed it down to either B or C, but I'm not sure because they both don't use a letter or number twice as x. So I'm not sure which one is a function.

Answer 1

to be a function, each member of A must map to a single member of B.

A is not a function: c-->2 and c-->3
B is
C is not, since it does not map A onto B
D is