16. If the sum to n terms of a series is n2 +2n, show that theseries i – InterviewSolution

1.	16. If the sum to n terms of a series is n2 +2n, show that theseries is an A.P.
Answer» Sn= n^2 +2nS1=1^2 + 2×1= 1+2=3S2= 2^2 + 2×2 = 4+4=8a1=3 ,a2= 8-3=5S3= 3^2 + 2x3= 9+ 6=15a3=S3-S2=15-8=7AP = 3,5,7......with common difference= 2

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