If Sn,the sum of first n terms of an ap is given by Sn=5n²+3n, then find its nth term

If Sn,the sum of first n terms of an ap is given by Sn=5n²+3n, then f

1.	If Sn,the sum of first n terms of an ap is given by Sn=5n²+3n, then find its nth term
Answer» An= Sn - Sn-1, S1= 5×1 +3×1 = 5+3=8 S1 is the sum of only first term .....i.e S1=aTherefore when n=1, S1=5(1^2)+3×1=8.....Therefore a=S1=8Again, n=2, ..... S2=5(2^2)+3×2=26....a+a2=S2.. or 8+a2=26...... therefore a2=18Now d=a2-a=18-8=10.....Hence nth term=a+(n-1)d = 8+(n-1)10 = 8+10n-10 = 10n-2