Question

If $S_n=nP+\frac{n(n-1)2}{Q}$, where $S_n$ denotes the sum of the first $n$ terms of an $A.P$., then find the common difference.

Answer 1

$Sn=nP+\frac{n(n-1)2}{Q}$

$Sn=\frac{n}{2}[2a+\frac{(n-1)d}{2}]$

$=na+n(n-1)d$

$a=pd=2/Q$