SOLUTION: Find Sn for the arithmetic series in which a1=an=13, n=7. Thanks

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Question 41708: Find Sn for the arithmetic series in which a1=an=13, n=7.
Thanks
Found 2 solutions by venugopalramana, Nate:
Answer by venugopalramana(3286) About Me  (Show Source):
You can put this solution on YOUR website!
Find Sn for the arithmetic series in which a1=an=13, n=7.
SN=(N/2)(A1+AN)=(7/2)(13+13)=91

Answer by Nate(3500) About Me  (Show Source):
You can put this solution on YOUR website!
Think:
First Term: 13
Last Term: 13
Without using the equation we can get:
13 + 13 + 13 + 13 + 13 + 13 + 13 = 7*13 = 91