If A = {1, 2, {1, 2}}, how many elements does A have?
Answer and explanation
Correct answer: 3
The set A contains three elements: the number 1, the number 2, and the set {1, 2}. The inner set {1, 2} is counted as one single element of A, not as two additional elements. Therefore, n(A) = 3. This illustrates that a set itself can be an element of another set, and elements must be counted according to how they are listed at the outermost level.
Frequently asked questions
What is the correct answer to this question?
3
Why is this the correct answer?
The set A contains three elements: the number 1, the number 2, and the set {1, 2}. The inner set {1, 2} is counted as one single element of A, not as two additional elements. Therefore, n(A) = 3. This illustrates that a set itself can be an element of another set, and elements must be counted according to how they are listed at the outermost level.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Equal sets and Subsets.
