SOLUTION: Find n if Sn = 63, a1 = 21, and d = -4

SOLUTION: Find n if Sn = 63, a1 = 21, and d = -4

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Question 976760: Find n if Sn = 63, a1 = 21, and d = -4
Answer by FrankM(1040) (Show Source): You can put this solution on YOUR website!

let's enter what we were given -

I'd use the quadratic equation here, note, the solutions result in 4.5 and 7, but the answer must be an integer.

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