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If (a=80), (d=-5), and (n=14), find (a_n).
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Answer and explanation
Correct answer: 15
The nth term of an AP is \(a_n=a+(n-1)d\). Therefore, \(a_{14}=80+(14-1)(-5)=80-65=15\). Hence, 15 is correct. A common error is to get 20 by using 12 instead of \(n-1\). Exam tip: Keep a negative \(d\) in brackets while multiplying.
Frequently asked questions
What is the correct answer to this question?
15
Why is this the correct answer?
The nth term of an AP is \(a_n=a+(n-1)d\). Therefore, \(a_{14}=80+(14-1)(-5)=80-65=15\). Hence, 15 is correct. A common error is to get 20 by using 12 instead of \(n-1\). Exam tip: Keep a negative \(d\) in brackets while multiplying.
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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