Find the (11)th term of the AP (48,42,36,30,\ldots).
Answer and explanation
Correct answer: \(-12\)
For this AP, the first term is \(a=48\) and the common difference is \(d=42-48=-6\). The \(n\)th term is \(a_n=a+(n-1)d\). Hence, \(a_{11}=48+(11-1)(-6)=48-60=-12\). Therefore, \(-12\) is correct. A value such as \(-14\) may result from miscounting terms or using \(n\) instead of \((n-1)\). Exam tip: always use \((n-1)\) in the formula for the \(n\)th term.
Frequently asked questions
What is the correct answer to this question?
\(-12\)
Why is this the correct answer?
For this AP, the first term is \(a=48\) and the common difference is \(d=42-48=-6\). The \(n\)th term is \(a_n=a+(n-1)d\). Hence, \(a_{11}=48+(11-1)(-6)=48-60=-12\). Therefore, \(-12\) is correct. A value such as \(-14\) may result from miscounting terms or using \(n\) instead of \((n-1)\). Exam tip: always use \((n-1)\) in the formula for the \(n\)th term.
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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