Question
Fri May 25, 2012 By:

If Sn = 3n2 + 1, then find 'd'.

Expert Reply
Sat May 26, 2012

Sn=3n2+1

So, a = S1 = (3x1)+ 1 = 4 [Substituting n=1]

Then, S2 = (3x22) + 1 = 13 [Substituting n=2]

Now, a2 = S2-a = 13-4 = 9

d = a2-a = 9-4 = 5

 

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