Which is the correct rule for the sequence (5,14,29,50,\ldots)?
Answer and explanation
Correct answer: \(a_n=3n^2+2\)
The correct rule is \(a_n=3n^2+2\). Substituting \(n=1,2,3,4\) gives \(5,14,29,50\), respectively. The closest distractor, \(a_n=3n^2+n\), gives \(4\) when \(n=1\), so it cannot represent the sequence. Exam tip: verify a proposed general rule using at least the first two or three terms.
Frequently asked questions
What is the correct answer to this question?
\(a_n=3n^2+2\)
Why is this the correct answer?
The correct rule is \(a_n=3n^2+2\). Substituting \(n=1,2,3,4\) gives \(5,14,29,50\), respectively. The closest distractor, \(a_n=3n^2+n\), gives \(4\) when \(n=1\), so it cannot represent the sequence. Exam tip: verify a proposed general rule using at least the first two or 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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