Let A = {1, 2, 3, 4, 6}. Let R be the relation on A defined by {(a, b): a, b ∈ A, a is exactly divisible by b}. Write R in roster form. Find its domain and range.

Range is same as codomain

We have A = {1, 2, 3, 4, 6},

R= {(a, b): a, b ∈ A, a is exactly divisible by b}

∴ R = {(1, 1), (2, 1), (3, 1), (4, 1), (6, 1), (2, 2), (4, 2), (6, 2), (3, 3), (6, 3), (4, 4), (6, 6)}

Domain of R is {1, 2, 3, 4, 6}. 

Range is of R = {1, 2, 3, 4, 6}.

Here Range is same as codomain.