Which option is the correct set-builder form of J={3,6,9,12}?
Answer and explanation
Correct answer: J={x: x is a multiple of 3 and 3≤x≤12}
The listed elements 3, 6, 9, and 12 are all multiples of 3. Restricting x to the inclusive interval 3≤x≤12 gives exactly those four multiples: 3, 6, 9, and 12. Thus option A reproduces J without adding or losing an element. The other descriptions produce different sets: factors of 3 are much fewer, and even or prime numbers do not match the roster.
Frequently asked questions
What is the correct answer to this question?
J={x: x is a multiple of 3 and 3≤x≤12}
Why is this the correct answer?
The listed elements 3, 6, 9, and 12 are all multiples of 3. Restricting x to the inclusive interval 3≤x≤12 gives exactly those four multiples: 3, 6, 9, and 12. Thus option A reproduces J without adding or losing an element. The other descriptions produce different sets: factors of 3 are much fewer, and even or prime numbers do not match the roster.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems. Topic: General chapter practice.
