How should B={2,4,6,8,...,40} be written in set-builder form?
Answer and explanation
Correct answer: B={x:x=2n, n∈N, 1≤n≤20}
The governing concept is representing a finite pattern with a parameter. Every member of B is twice a natural number, so write x=2n. Taking n=1,2,...,20 produces 2,4,6,...,40, and the inclusive bounds 1≤n≤20 include both endpoints. Option B omits endpoints, C gives squares, and D gives odd numbers. Thus option A is correct.
Frequently asked questions
What is the correct answer to this question?
B={x:x=2n, n∈N, 1≤n≤20}
Why is this the correct answer?
The governing concept is representing a finite pattern with a parameter. Every member of B is twice a natural number, so write x=2n. Taking n=1,2,...,20 produces 2,4,6,...,40, and the inclusive bounds 1≤n≤20 include both endpoints. Option B omits endpoints, C gives squares, and D gives odd numbers. Thus option A is correct.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Number Systems.
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