What will be the (15)th term of the AP (100,92,84,\ldots)?
Answer and explanation
Correct answer: -12
In this AP, the first term is \(a=100\) and the common difference is \(d=92-100=-8\). The \(n\)th term is given by \(a_n=a+(n-1)d\). Therefore, \(a_{15}=100+(15-1)(-8)=100-112=-12\). Hence, \(-12\) is correct. An answer such as \(-4\) can result from using the wrong term count instead of \(n-1\). Exam tip: always check the negative sign of the common difference.
Frequently asked questions
What is the correct answer to this question?
-12
Why is this the correct answer?
In this AP, the first term is \(a=100\) and the common difference is \(d=92-100=-8\). The \(n\)th term is given by \(a_n=a+(n-1)d\). Therefore, \(a_{15}=100+(15-1)(-8)=100-112=-12\). Hence, \(-12\) is correct. An answer such as \(-4\) can result from using the wrong term count instead of \(n-1\). Exam tip: always check the negative sign of the common difference.
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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