If A = {1, 2, 3} and B = {x ∈ ℕ : x³ ≤ 27}, which statement is correct?
Answer and explanation
Correct answer: A = B
For natural numbers, test the values around the boundary: 1³ = 1, 2³ = 8, and 3³ = 27, so 1, 2, and 3 satisfy x³ ≤ 27. The next natural number does not, because 4³ = 64 > 27. Therefore B = {1, 2, 3}, which is exactly the same collection of elements as A. Hence A = B; both sets are finite and equal.
Frequently asked questions
What is the correct answer to this question?
A = B
Why is this the correct answer?
For natural numbers, test the values around the boundary: 1³ = 1, 2³ = 8, and 3³ = 27, so 1, 2, and 3 satisfy x³ ≤ 27. The next natural number does not, because 4³ = 64 > 27. Therefore B = {1, 2, 3}, which is exactly the same collection of elements as A. Hence A = B; both sets are finite and equal.
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.