If A = {x ∈ ℤ : x² ≤ x}, what is n(A)?
Answer and explanation
Correct answer: 2
Move all terms to one side: x² − x ≤ 0, which factors as x(x − 1) ≤ 0. The real solution interval is 0 ≤ x ≤ 1. Among integers, the only values in this closed interval are 0 and 1, so A = {0, 1}. Therefore, the number of elements is n(A) = 2. Both endpoints are included because the inequality is non-strict.
Frequently asked questions
What is the correct answer to this question?
2
Why is this the correct answer?
Move all terms to one side: x² − x ≤ 0, which factors as x(x − 1) ≤ 0. The real solution interval is 0 ≤ x ≤ 1. Among integers, the only values in this closed interval are 0 and 1, so A = {0, 1}. Therefore, the number of elements is n(A) = 2. Both endpoints are included because the inequality is non-strict.
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.