In the sequence (9,18,27,36,\ldots), which term is (81)?
Answer and explanation
Correct answer: ninth term
This sequence consists of multiples of 9, so its nth term is \(a_n=9n\). Putting \(9n=81\) gives \(n=9\). Therefore, 81 is the ninth term. The eighth term is \(9\times8=72\), so it is not correct. Exam tip: To find a term number, equate the given value to the nth-term formula and solve for \(n\).
Frequently asked questions
What is the correct answer to this question?
ninth term
Why is this the correct answer?
This sequence consists of multiples of 9, so its nth term is \(a_n=9n\). Putting \(9n=81\) gives \(n=9\). Therefore, 81 is the ninth term. The eighth term is \(9\times8=72\), so it is not correct. Exam tip: To find a term number, equate the given value to the nth-term formula and solve for \(n\).
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: nth term.
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