Mathematics for IGCSE & O level - Sets (Section 2 - No. 40)

If U = {1, 2, 3, 4, 5, 6}, A = {1, 2, 3}, and B = {3, 4, 5}, what is (A ∪ B)'?

{6}

{1, 2, 3, 4, 5}

{3}

{1, 2, 3, 4, 5, 6}

A ∪ B = {1, 2, 3, 4, 5}. Then, (A ∪ B)' is the complement of (A ∪ B) relative to U, which is {6}.