Which option gives the correct roster form of A = {x : x ∈ N and 2x + 1 < 10}?
Answer and explanation
Correct answer: A = {1, 2, 3, 4}
The governing concept is converting a set-builder condition into roster form. Solve 2x+1<10: subtracting 1 gives 2x<9, and dividing by 2 gives x<4.5. Under the stated convention N={1,2,3,...}, the allowed values are 1,2,3,4. Therefore A={1,2,3,4}, so option A is correct. Zero is excluded here, and 5 fails the inequality.
Frequently asked questions
What is the correct answer to this question?
A = {1, 2, 3, 4}
Why is this the correct answer?
The governing concept is converting a set-builder condition into roster form. Solve 2x+1<10: subtracting 1 gives 2x<9, and dividing by 2 gives x<4.5. Under the stated convention N={1,2,3,...}, the allowed values are 1,2,3,4. Therefore A={1,2,3,4}, so option A is correct. Zero is excluded here, and 5 fails the inequality.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems. Topic: General chapter practice.
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