2. Let R = {((a, b),(c, d)) : ad = bc} be the equivalence relation defined on A = Z (Z {0}) from Concept 5.5(c).

Describe the elements of the equivalence class [(1, 2)].

Describe the elements of the equivalence class [(2, 3)].

Describe the elements of the equivalence class [(3, 6)].

Is it true that [(1, 2)] = [(3, 6)]? 5. What is [(1, 2)] [(2, 3)]?

Describe in simple language what it means for (a, b) and (c, d) to be in the same equivalence class.

What familiar set does the partition {[(a, b)] : (a, b) A} of A look like?