SOLUTION: Will someone please help me. I don't know where to begin on this problem. I have to show all my work. Find Sn for the arithmetic series in which A1=-11, An=13, and n=7. I have

Question 171173: Will someone please help me. I don't know where to begin on this problem. I have to show all my work.
Find Sn for the arithmetic series in which A1=-11, An=13, and n=7.
I have a big test later today and really need help.
Thanks
Answer by monika_p(71) (Show Source): You can put this solution on YOUR website!
Formula for an arithmetic series is:

You have given A1 = -11
An = 13
n = 7
substitute and simplify :

The answer is:
Sn = 7
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