If Z = {x : x ∈ ℤ, x² ≤ 4}, how many elements does Z have?
Answer and explanation
Correct answer: 5
The inequality x² ≤ 4 is equivalent to |x| ≤ 2, so −2 ≤ x ≤ 2. The integers in this closed interval are −2, −1, 0, 1, and 2. Therefore Z = {−2, −1, 0, 1, 2}, which has five elements. Unlike a strict inequality, ≤ includes both boundary values −2 and 2.
Frequently asked questions
What is the correct answer to this question?
5
Why is this the correct answer?
The inequality x² ≤ 4 is equivalent to |x| ≤ 2, so −2 ≤ x ≤ 2. The integers in this closed interval are −2, −1, 0, 1, and 2. Therefore Z = {−2, −1, 0, 1, 2}, which has five elements. Unlike a strict inequality, ≤ includes both boundary values −2 and 2.
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.