If A = {1, 2, 3, 4} and B = {3, 4, 5, 6}, what is the union of A − B and B − A?
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Answer and explanation
Correct answer: {1, 2, 5, 6}
First calculate each difference separately. A − B contains elements in A but not B, so A − B = {1, 2}. Similarly, B − A = {5, 6}, because 5 and 6 are not in A. Their union is therefore {1, 2} ∪ {5, 6} = {1, 2, 5, 6}. The common elements 3 and 4 are excluded, so option A is correct.
Frequently asked questions
What is the correct answer to this question?
{1, 2, 5, 6}
Why is this the correct answer?
First calculate each difference separately. A − B contains elements in A but not B, so A − B = {1, 2}. Similarly, B − A = {5, 6}, because 5 and 6 are not in A. Their union is therefore {1, 2} ∪ {5, 6} = {1, 2, 5, 6}. The common elements 3 and 4 are excluded, so option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).
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