If A = {x : x ∈ N and 3 ≤ x < 9}, which is the roster form of A?
Answer and explanation
Correct answer: A = {3, 4, 5, 6, 7, 8}
The symbol 3 ≤ x includes 3, while x < 9 excludes 9. Therefore the natural numbers satisfying both inequalities are 3, 4, 5, 6, 7 and 8. The correct roster form is A = {3, 4, 5, 6, 7, 8}. Options B and D wrongly omit or shift the lower endpoint, and option C incorrectly includes 9.
Frequently asked questions
What is the correct answer to this question?
A = {3, 4, 5, 6, 7, 8}
Why is this the correct answer?
The symbol 3 ≤ x includes 3, while x < 9 excludes 9. Therefore the natural numbers satisfying both inequalities are 3, 4, 5, 6, 7 and 8. The correct roster form is A = {3, 4, 5, 6, 7, 8}. Options B and D wrongly omit or shift the lower endpoint, and option C incorrectly includes 9.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems.
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