If A ∩ (B ∪ C) = A, which conclusion must be true?
Answer and explanation
Correct answer: A ⊆ B ∪ C
For any sets X and Y, the equality X ∩ Y = X holds exactly when every element of X is also an element of Y; in other words, X ⊆ Y. Here X is A and Y is B ∪ C. Thus every element of A must belong to B or C, so A ⊆ B ∪ C. No reverse inclusion is required.
Frequently asked questions
What is the correct answer to this question?
A ⊆ B ∪ C
Why is this the correct answer?
For any sets X and Y, the equality X ∩ Y = X holds exactly when every element of X is also an element of Y; in other words, X ⊆ Y. Here X is A and Y is B ∪ C. Thus every element of A must belong to B or C, so A ⊆ B ∪ C. No reverse inclusion is required.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).