If A = {x : x ∈ ℤ, x² ≤ 4} and B = {-1, 0, 1, 3}, what is A ∩ B?
Answer and explanation
Correct answer: {-1, 0, 1}
Because x is an integer and x² ≤ 4, we have |x| ≤ 2, so -2 ≤ x ≤ 2. Therefore A = {-2, -1, 0, 1, 2}. The intersection keeps only elements common to A and B. Comparing B = {-1, 0, 1, 3} with A, the common elements are -1, 0, and 1; 3 is not in A. Hence A ∩ B = {-1, 0, 1}, so option B is correct.
Frequently asked questions
What is the correct answer to this question?
{-1, 0, 1}
Why is this the correct answer?
Because x is an integer and x² ≤ 4, we have |x| ≤ 2, so -2 ≤ x ≤ 2. Therefore A = {-2, -1, 0, 1, 2}. The intersection keeps only elements common to A and B. Comparing B = {-1, 0, 1, 3} with A, the common elements are -1, 0, and 1; 3 is not in A. Hence A ∩ B = {-1, 0, 1}, so option B is correct.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).