Question

List the ordered pairs in the relation R from A = {0, 1, 2, 3, 4} to B = {0, 1, 2, 3}, where (a, b) ∈ R if and only if a | b.

Answer 1

Let $(a, b) ∈ R$ if and only if $a ∣ b.$ It follows that $R=\{(1,0),(1,1),(1,2),(1,3),(2,0),(2,2),\\(3,0),(3,3),(4,0)\}.$