Question

Let f = {(x, y) | x, y ∈ N and y = 2x} be a relation on N. Find the domain, co-domain and range. Is this relation a function?

Answer 1

F = {(x, y)|x, y ∈ N and y = 2x}

x = {1, 2, 3, ...}

y = {1 × 2, 2 × 2, 3 × 2, 4 × 2, 5 × 2 …}

f = {(1, 2), (2, 4), (3, 6), (4, 8), (5, 10), …}

Domain of R = {1, 2, 3, 4 …}

Co-domain = {1, 2, 3 …}

Range of R = {2, 4, 6, 8, 10, ...}

Yes, this relation is a function.