Mathematics for IGCSE & O level - Sets (Section 2 - No. 39)
Given sets A, B, and C, which of the following is associative?
A ∪ B = B ∪ A
(A ∩ B) ∩ C = A ∩ (B ∩ C)
A ∩ B = B ∩ A
(A ∪ B) ∩ C = A ∪ (B ∩ C)
Uitleg
Associativity applies to the operations, where grouping doesn't change the results. (A ∩ B) ∩ C = A ∩ (B ∩ C).