In an AP, (a=15) and (d=-2). What is the (13)th term?
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Answer and explanation
Correct answer: \(-9\)
The \(n\)th term of an AP is \(a_n=a+(n-1)d\). Therefore, \(a_{13}=15+(13-1)(-2)=15-24=-9\). The option \(-7\) can result from using the term number or common difference incorrectly. Exam tip: for the \(n\)th term, always use \(n-1\) common differences, not \(n\).
Frequently asked questions
What is the correct answer to this question?
\(-9\)
Why is this the correct answer?
The \(n\)th term of an AP is \(a_n=a+(n-1)d\). Therefore, \(a_{13}=15+(13-1)(-2)=15-24=-9\). The option \(-7\) can result from using the term number or common difference incorrectly. Exam tip: for the \(n\)th term, always use \(n-1\) common differences, not \(n\).
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Finding the $n$th term of an AP.
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