If A − B = ∅ and B − C = ∅, which conclusion is correct?
Answer and explanation
Correct answer: A ⊆ C
A − B = ∅ means that no element of A lies outside B, so A ⊆ B. Likewise, B − C = ∅ means B ⊆ C. Subset inclusion is transitive: if every element of A is in B and every element of B is in C, then every element of A is in C. Therefore A ⊆ C must be true. Equality or disjointness is not forced.
Frequently asked questions
What is the correct answer to this question?
A ⊆ C
Why is this the correct answer?
A − B = ∅ means that no element of A lies outside B, so A ⊆ B. Likewise, B − C = ∅ means B ⊆ C. Subset inclusion is transitive: if every element of A is in B and every element of B is in C, then every element of A is in C. Therefore A ⊆ C must be true. Equality or disjointness is not forced.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).