If Sum of the first n terms of an AP is given by Sum of n terms=5n^2+3n,then find its nth term

If Sum of the first n terms of an AP is given by Sum of n terms=5n^2+3

1.	If Sum of the first n terms of an AP is given by Sum of n terms=5n^2+3n,then find its nth term
Answer» Give Sn=5n2+3n ---------(1)Then Sn-1=5(n-1)2+3(n-1) [on replacing n by n-1 in eq.(1)] =5(n2-2n+1)+3n-3 =5n2-10n+5+3n-3 =5n2-7n+2So nth\xa0term of A.P. is given by an=Sn\xa0- Sn-1 an=5n2+3n-(5n2-7n+2) =5n2+3n-5n2+7n-2 =10n-2[CONCEPT USED:- IF THE SUM OF n terms OF AN A.P. IS GIVEN Sn\xa0THEN THE nth term IS GIVEN BY an=Sn\xa0- Sn-1\xa0\xa0]