If A △ B = (A ∩ B′) ∪ (A′ ∩ B), what is (A △ B)′ equal to?
Answer and explanation
Correct answer: (A ∩ B) ∪ (A′ ∩ B′)
The symmetric difference A △ B consists of elements belonging to exactly one of A and B. Its complement therefore consists of elements that belong to both sets or to neither set. The ‘both’ part is A ∩ B, and the ‘neither’ part is A′ ∩ B′. Taking their union gives (A △ B)′ = (A ∩ B) ∪ (A′ ∩ B′).
Frequently asked questions
What is the correct answer to this question?
(A ∩ B) ∪ (A′ ∩ B′)
Why is this the correct answer?
The symmetric difference A △ B consists of elements belonging to exactly one of A and B. Its complement therefore consists of elements that belong to both sets or to neither set. The ‘both’ part is A ∩ B, and the ‘neither’ part is A′ ∩ B′. Taking their union gives (A △ B)′ = (A ∩ B) ∪ (A′ ∩ B′).
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Complement of a Set and Its Properties.