If A ⊆ B ⊆ C ⊆ U, which relation is always true?
Answer and explanation
Correct answer: C′ ⊆ B′ ⊆ A′
Taking complements reverses the direction of inclusion. Since every element of A is in B and every element of B is in C, any element outside C is certainly outside B and outside A. Therefore C′ ⊆ B′ ⊆ A′. Equality is not guaranteed because the original inclusions may be proper.
Frequently asked questions
What is the correct answer to this question?
C′ ⊆ B′ ⊆ A′
Why is this the correct answer?
Taking complements reverses the direction of inclusion. Since every element of A is in B and every element of B is in C, any element outside C is certainly outside B and outside A. Therefore C′ ⊆ B′ ⊆ A′. Equality is not guaranteed because the original inclusions may be proper.
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.