Find the (9)th term of the AP (3,8,13,18,\ldots).
Answer and explanation
Correct answer: 43
In this AP, the first term is \(a=3\) and the common difference is \(d=8-3=5\). The \(n\)th term is \(a_n=a+(n-1)d\). Therefore, \(a_9=3+(9-1)\times5=3+40=43\). Hence, 43 is correct. The value 38 can result from using an incorrect term count in place of \(n-1\). Exam tip: identify the first term and common difference before substituting \(n-1\) in the formula.
Frequently asked questions
What is the correct answer to this question?
43
Why is this the correct answer?
In this AP, the first term is \(a=3\) and the common difference is \(d=8-3=5\). The \(n\)th term is \(a_n=a+(n-1)d\). Therefore, \(a_9=3+(9-1)\times5=3+40=43\). Hence, 43 is correct. The value 38 can result from using an incorrect term count in place of \(n-1\). Exam tip: identify the first term and common difference before substituting \(n-1\) in the formula.
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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