If A ∪ B = A and A \ B = ∅, which conclusion is correct?
Answer and explanation
Correct answer: A = B
The equality A ∪ B = A means that every element of B is already in A, so B ⊆ A. The condition A \ B = ∅ means that no element of A lies outside B; therefore A ⊆ B. Since each set is a subset of the other, the two sets are equal. Hence A = B, and no claim that either set is empty is justified.
Frequently asked questions
What is the correct answer to this question?
A = B
Why is this the correct answer?
The equality A ∪ B = A means that every element of B is already in A, so B ⊆ A. The condition A \ B = ∅ means that no element of A lies outside B; therefore A ⊆ B. Since each set is a subset of the other, the two sets are equal. Hence A = B, and no claim that either set is empty is justified.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).