Ok I'm up to the next step in set theory and am having trouble determining if set relations are injective, sirjective or bijective.

Say we are matching the members of a set "A" **to** a set "B"

Injective means that every member of "A" has a** unique** matching member in "B". You won't get two "A"s pointing to one "B", but you could have a "B" without a matching "A"

Surjective means that every "B" has **at least one** matching "A" (maybe more than one).

Bijective means both. So we have a perfect 1-1 relationship

Let

A = {1,2,3,4,5}and B = {0,6,7,8,9} (a) How many functions f: A =>B are there?

(b) How many injective functions f : A => B are there?

(c) How many surjective functions f : A =>B are there?

(d) How many bijective functions f : A =>B such that f(3) = 6 are there?