Which option is the correct roster form of J = {x : x ∈ N, x = 3n − 1, 1 ≤ n ≤ 5}?
Answer and explanation
Correct answer: J = {2, 5, 8, 11, 14}
Use the defining formula for each allowed value of n. When n = 1, 2, 3, 4, and 5, x = 3n − 1 gives 2, 5, 8, 11, and 14 respectively. The inequality includes both endpoints, so n = 5 must be used and 14 cannot be omitted. Option B lists multiples of 3, C follows 3n − 2, and D misses the final value. Hence A is correct.
Frequently asked questions
What is the correct answer to this question?
J = {2, 5, 8, 11, 14}
Why is this the correct answer?
Use the defining formula for each allowed value of n. When n = 1, 2, 3, 4, and 5, x = 3n − 1 gives 2, 5, 8, 11, and 14 respectively. The inequality includes both endpoints, so n = 5 must be used and 14 cannot be omitted. Option B lists multiples of 3, C follows 3n − 2, and D misses the final value. Hence A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Sets and their representations.
