Which is the (n)th term of the sequence (10,7,4,1,-2,\ldots)?
Answer and explanation
Correct answer: \(13-3n\)
This is an arithmetic sequence because each successive term decreases by 3. Hence, \(a_1=10\) and \(d=-3\). Using \(a_n=a_1+(n-1)d\), we get \(a_n=10+(n-1)(-3)=13-3n\). In option A, putting \(n=1\) gives 7, not the first term 10. Exam tip: verify an nth-term formula by substituting \(n=1\) and checking the first term.
Frequently asked questions
What is the correct answer to this question?
\(13-3n\)
Why is this the correct answer?
This is an arithmetic sequence because each successive term decreases by 3. Hence, \(a_1=10\) and \(d=-3\). Using \(a_n=a_1+(n-1)d\), we get \(a_n=10+(n-1)(-3)=13-3n\). In option A, putting \(n=1\) gives 7, not the first term 10. Exam tip: verify an nth-term formula by substituting \(n=1\) and checking the first term.
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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