If the sum of n terms of an A.P. is `(p n+q n^2)` , where p and q are constants, find the common difference.

Explanation

Given `S_n=Pn+Qn^2`


`:. T_n=S_n-S_(n-1)`


`=Pn+Qn^2-[P(n-1)+Q(n-1)^2]`


`=P-Q+2nQ`


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