passwella.
Menu

UI Post-UTME Mathematics 2014 Question 8

Question 8

Sets

If N is the set of natural numbers and A = {x : |x − 1| < 2, x ∈ N}, then

  1. A.A = {1}
  2. B.A = {1, 2}
  3. C.A = {0, 1, 2}
  4. D.A = {−1, 0, 1, 2}
Show the answer and explanation

Answer: B (A = {1, 2})

Explanation

|x − 1| < 2 means −2 < x − 1 < 2, so −1 < x < 3. The natural numbers (counting numbers 1, 2, 3, …) in this range are 1 and 2, so A = {1, 2}.