SOLUTION: determine the number of terms in the arithmetic series... a sub 1 = -27 a sub n = -51 s sub n = -195

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Question 646268: determine the number of terms in the arithmetic series...
a sub 1 = -27
a sub n = -51
s sub n = -195
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

arithmetic series

S%5Bn%5D+=%28n%28a%5B1%5D%2Ba%5Bn%5D%29%29%2F2****

 -195 = n(-27 + -51)/2

 -195 =( -78/2)n

 -195/-39 = n

     5 = n

Note: a%5B5%5D = -27 + 4d = -51, d = -6

{-27,-33,-39,-45,-51}