What is the (21)st term of the AP (7,16,25,34,\ldots)?
Answer and explanation
Correct answer: 187
In this AP, the first term is \(a=7\) and the common difference is \(d=16-7=9\). The \(n\)th term is given by \(a_n=a+(n-1)d\). Therefore, \(a_{21}=7+(21-1)\times9=7+180=187\). Hence, 187 is correct. Getting 185 usually results from using an incorrect number of common differences. Exam tip: from the first term to the \(n\)th term, add the common difference \(n-1\) times.
Frequently asked questions
What is the correct answer to this question?
187
Why is this the correct answer?
In this AP, the first term is \(a=7\) and the common difference is \(d=16-7=9\). The \(n\)th term is given by \(a_n=a+(n-1)d\). Therefore, \(a_{21}=7+(21-1)\times9=7+180=187\). Hence, 187 is correct. Getting 185 usually results from using an incorrect number of common differences. Exam tip: from the first term to the \(n\)th term, add the common difference \(n-1\) times.
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.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
