If the universal set is U = ℝ, A = (−∞, 0] and B = [2, ∞), what is A′ ∩ B′?
Answer and explanation
Correct answer: (0, 2)
Complements are taken relative to ℝ. Since A includes all real numbers up to and including 0, A′ = (0, ∞). Since B includes all real numbers from 2 onward, including 2, B′ = (−∞, 2). Their intersection is therefore the real interval (0, 2). Both endpoints are excluded: 0 is in A and 2 is in B.
Frequently asked questions
What is the correct answer to this question?
(0, 2)
Why is this the correct answer?
Complements are taken relative to ℝ. Since A includes all real numbers up to and including 0, A′ = (0, ∞). Since B includes all real numbers from 2 onward, including 2, B′ = (−∞, 2). Their intersection is therefore the real interval (0, 2). Both endpoints are excluded: 0 is in A and 2 is in 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.