Question

If A and B be any two sets, then (A∩B)′ is equal to- (A) A′∩B′ (B) A′∪B′ (C) A∩B (D) A∪B

Answer 1

Answer: A′∪B′ which is the 2nd answer choice

Reason: We use De Morgan's law. This is where we negate each piece, and flip the "set intersection" to "set union". I recommend making a Venn Diagram to prove why this trick works.