Question

if the sum of n term of an ap is np+1/2n(n-1)Q, where P and Q are constants, find the common difference of the AP.

Answer 1

common difference d = sum of(n+1)terms - sum of n terms 

=>d=(nP+n+1)/(2Qn(n+1))-[(nP+1)/(2nQ(n... 

=(n^2 P+n^2+n-nP-n-1-n^2 P-n-nP-1) / (2Qn(n^2-1)) 

=(n^2-2nP-n-2) / (2Qn(n^2-1))

hope it helps!!