If A ⊆ U, what are A ∪ A′ and A ∩ A′, respectively?
Answer and explanation
Correct answer: U, ∅
For every element of the universal set U, either it belongs to A or it does not belong to A. The elements not in A form A′, so combining A and A′ gives the whole universal set: A ∪ A′ = U. No element can simultaneously belong to A and its complement, so A ∩ A′ = ∅. Therefore, option A is correct.
Frequently asked questions
What is the correct answer to this question?
U, ∅
Why is this the correct answer?
For every element of the universal set U, either it belongs to A or it does not belong to A. The elements not in A form A′, so combining A and A′ gives the whole universal set: A ∪ A′ = U. No element can simultaneously belong to A and its complement, so A ∩ A′ = ∅. Therefore, option A is correct.
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.