What kind of set is A = {x : x ∈ N, x² + 2x + 1 = 0}?
Answer and explanation
Correct answer: Empty set
Factor the equation as x² + 2x + 1 = (x + 1)² = 0. Its only real and integer solution is x = −1. However, −1 is not a natural number, so it does not satisfy the restriction x ∈ N. Consequently, no permitted value belongs to A, which means A = ∅, the empty set.
Frequently asked questions
What is the correct answer to this question?
Empty set
Why is this the correct answer?
Factor the equation as x² + 2x + 1 = (x + 1)² = 0. Its only real and integer solution is x = −1. However, −1 is not a natural number, so it does not satisfy the restriction x ∈ N. Consequently, no permitted value belongs to A, which means A = ∅, the empty set.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: The Empty Set, Finite and Infinite Sets, Equal Sets.