If (a_n=9-2n), which term is equal to (-31)?
Answer and explanation
Correct answer: 20th term
Given \(a_n=9-2n\), put \(a_n=-31\): \(9-2n=-31\). Thus, \(-2n=-40\), so \(n=20\). Therefore, the 20th term is \(-31\). The 19th term is \(9-2(19)=-29\), so it is not correct. Exam tip: To find a particular term number, substitute the given term value for \(a_n\) and solve for \(n\).
Frequently asked questions
What is the correct answer to this question?
20th term
Why is this the correct answer?
Given \(a_n=9-2n\), put \(a_n=-31\): \(9-2n=-31\). Thus, \(-2n=-40\), so \(n=20\). Therefore, the 20th term is \(-31\). The 19th term is \(9-2(19)=-29\), so it is not correct. Exam tip: To find a particular term number, substitute the given term value for \(a_n\) 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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