If P(A) = {∅, {5}}, what is the original set A?
Answer and explanation
Correct answer: {5}
For any set A, its power set P(A) always contains the empty set and A itself. Here P(A) has exactly two elements: ∅ and {5}. Since the non-empty member is the whole original set, A must be {5}. This also agrees with the rule that a one-element set has 2¹ = 2 subsets: ∅ and {5}.
Frequently asked questions
What is the correct answer to this question?
{5}
Why is this the correct answer?
For any set A, its power set P(A) always contains the empty set and A itself. Here P(A) has exactly two elements: ∅ and {5}. Since the non-empty member is the whole original set, A must be {5}. This also agrees with the rule that a one-element set has 2¹ = 2 subsets: ∅ and {5}.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Power Set and Subsets.