SOLUTION: find n for the given sum of Sn 34+31+28+25+22+... Sn= -12

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Question 801679: find n for the given sum of Sn
34+31+28+25+22+...
Sn= -12
Answer by tommyt3rd(5050) About Me  (Show Source):
You can put this solution on YOUR website!
Sn=(n/2)(a1+a1+(n-1)d)
-12=(n/2)(34+34+(n-1)(-3))

leads to n=24