Question:
The $n$th term of an A.P., the sum of whose $n$ terms is $\mathrm{S}_{n}$, is
(a) $S_{n}+S_{n-1}$
(b) $S_{n}-S_{n-1}$
(c) $S_{n}+S_{n+1}$
(d) $S_{n}-S_{n+1}$
Solution:
A.P. we use following formula,
$a_{n}=S_{n}-S_{n-1}$
So, the $n^{\text {th }}$ term of the A.P. is given by $a_{n}=S_{n}-S_{n-1}$. Therefore, the correct option is (b).