If U = ℝ and A = (−∞, −5) ∪ [1, 4] ∪ (9, ∞), what is A′?
Answer and explanation
Correct answer: [−5, 1) ∪ (4, 9]
To find the complement in ℝ, reverse the inclusion of each interval and include the boundary points that were excluded from A. The point −5 is included in the complement, while 1 is excluded because it belongs to A. Similarly, 4 is excluded and 9 is included. Therefore A′ = [−5, 1) ∪ (4, 9].
Frequently asked questions
What is the correct answer to this question?
[−5, 1) ∪ (4, 9]
Why is this the correct answer?
To find the complement in ℝ, reverse the inclusion of each interval and include the boundary points that were excluded from A. The point −5 is included in the complement, while 1 is excluded because it belongs to A. Similarly, 4 is excluded and 9 is included. Therefore A′ = [−5, 1) ∪ (4, 9].
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.