Which general term is correct for the sequence (3,8,15,24,\ldots)?
Answer and explanation
Correct answer: \(a_n=n^2+2n\)
Substituting \(n=1,2,3,4\) into \(a_n=n^2+2n\) gives \(3,8,15,24\), respectively. Therefore, it is the correct general term. The close distractor \(a_n=n^2+1\) gives \(2\) when \(n=1\), so it is incorrect. Exam tip: verify a general term using at least the first three terms.
Frequently asked questions
What is the correct answer to this question?
\(a_n=n^2+2n\)
Why is this the correct answer?
Substituting \(n=1,2,3,4\) into \(a_n=n^2+2n\) gives \(3,8,15,24\), respectively. Therefore, it is the correct general term. The close distractor \(a_n=n^2+1\) gives \(2\) when \(n=1\), so it is incorrect. Exam tip: verify a general term using at least the first three terms.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Explicit or general rule.
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