Find the (12)th term of the AP (7,11,15,19,\ldots).
Answer and explanation
Correct answer: 51
In this AP, the first term is \(a=7\) and the common difference is \(d=11-7=4\). The \(n\)th term is \(a_n=a+(n-1)d\). Therefore, \(a_{12}=7+(12-1)\times4=7+44=51\). Hence, 51 is correct. The number 55 is not the 12th term; it would be the 13th term. 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?
51
Why is this the correct answer?
In this AP, the first term is \(a=7\) and the common difference is \(d=11-7=4\). The \(n\)th term is \(a_n=a+(n-1)d\). Therefore, \(a_{12}=7+(12-1)\times4=7+44=51\). Hence, 51 is correct. The number 55 is not the 12th term; it would be the 13th term. 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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