The sum of first n terms of an A.P.


The sum of first $n$ terms of an A.P. is $3 n^{2}+4 n$. Find the 25 th term of this A.P.


$S_{n}=3 n^{2}+4 n$

We know


$\therefore a_{n}=3 n^{2}+4 n-3(n-1)^{2}-4(n-1)$

$\Rightarrow a_{n}=6 n+1$


Leave a comment


Click here to get exam-ready with eSaral

For making your preparation journey smoother of JEE, NEET and Class 8 to 10, grab our app now.

Download Now