If the (n)th term of an arithmetic sequence is (a_n=6n-1), what is (a_{15})?
Answer and explanation
Correct answer: 89
The nth term is \(a_n=6n-1\). Substituting \(n=15\), we get \(a_{15}=6\times15-1=90-1=89\). Therefore, 89 is correct. The value 91 would result from ignoring the \(-1\) in the formula. Exam tip: for an nth-term question, substitute the required term number for \(n\) in the given formula.
Frequently asked questions
What is the correct answer to this question?
89
Why is this the correct answer?
The nth term is \(a_n=6n-1\). Substituting \(n=15\), we get \(a_{15}=6\times15-1=90-1=89\). Therefore, 89 is correct. The value 91 would result from ignoring the \(-1\) in the formula. Exam tip: for an nth-term question, substitute the required term number for \(n\) in the given formula.
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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