Which option reads Q = {1, 2, 3} correctly?
Answer and explanation
Correct answer: Q contains only 1, 2, and 3
The governing concept is roster notation for a set. Curly braces list the elements that belong to the set, and the absence of an ellipsis or a range means that no additional elements are implied. Hence Q has exactly the three distinct elements 1, 2, and 3. Option A states this correctly, including the important word “only.” Option B incorrectly adds 4, option C contradicts the presence of three listed elements, and option D falsely says that 3 is absent even though it appears explicitly. Therefore option A is the only correct reading.
Frequently asked questions
What is the correct answer to this question?
Q contains only 1, 2, and 3
Why is this the correct answer?
The governing concept is roster notation for a set. Curly braces list the elements that belong to the set, and the absence of an ellipsis or a range means that no additional elements are implied. Hence Q has exactly the three distinct elements 1, 2, and 3. Option A states this correctly, including the important word “only.” Option B incorrectly adds 4, option C contradicts the presence of three listed elements, and option D falsely says that 3 is absent even though it appears explicitly. Therefore option A is the only correct reading.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Common Questions. Topic: General chapter practice.
