Which general term is correct for the sequence (2,8,18,32,\ldots)?
Answer and explanation
Correct answer: \(a_n=2n^2\)
Substituting \(n=1,2,3,4\) in \(2n^2\) gives \(2,8,18,32\), respectively. Hence, the correct general term is \(a_n=2n^2\). The close distractor \(a_n=4n\) gives 8 for the second term, but it gives 4 rather than 2 when \(n=1\). Exam tip: verify a proposed general term using at least the first three terms.
Frequently asked questions
What is the correct answer to this question?
\(a_n=2n^2\)
Why is this the correct answer?
Substituting \(n=1,2,3,4\) in \(2n^2\) gives \(2,8,18,32\), respectively. Hence, the correct general term is \(a_n=2n^2\). The close distractor \(a_n=4n\) gives 8 for the second term, but it gives 4 rather than 2 when \(n=1\). Exam tip: verify a proposed 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.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
