SOLUTION: Find S15 for the series -1 + -3 + -5 + -7 +...

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Question 1126514: Find S15 for the series -1 + -3 + -5 + -7 +...
Answer by ikleyn(52787) About Me  (Show Source):
You can put this solution on YOUR website!
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= - (1 + 3 + 5 + 7 + . . . ) = -225 = -%2815%5E2%29.


HINT.  The sum of the first n odd positive integer numbers is equal to n%5E2.

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