If A = {1, 2, 3}, what is A ∪ ∅?
Answer and explanation
Correct answer: {1, 2, 3}
The empty set ∅ has no elements, so taking its union with A does not add anything. This follows from the identity property of union: for every set A, A ∪ ∅ = A. Substituting A = {1, 2, 3} gives A ∪ ∅ = {1, 2, 3}. Therefore option B is correct. Option A confuses union with intersection, while options C and D incorrectly add or remove elements.
Frequently asked questions
What is the correct answer to this question?
{1, 2, 3}
Why is this the correct answer?
The empty set ∅ has no elements, so taking its union with A does not add anything. This follows from the identity property of union: for every set A, A ∪ ∅ = A. Substituting A = {1, 2, 3} gives A ∪ ∅ = {1, 2, 3}. Therefore option B is correct. Option A confuses union with intersection, while options C and D incorrectly add or remove elements.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).
