SOLUTION: The sum n terms is given by sn=n/2(1+n) find the fifth term of the sequence

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Question 848491: The sum n terms is given by sn=n/2(1+n) find the fifth term of the sequence
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

S%5Bn%5D=%28n%2F2%29%282%2Aa%5B1%5D%2B+%28n-1%29d%29

S%5Bn%5D=%28+n%2F2%29%281%2Bn%29 d = 1 and 2a%5B1%5D+=+2, a%5B1%5D+=+1

{1, 2, 3, 4, 5, ....}  and S%5B5%5D=%28+5%2F2%29%286%29=+15

 a%5B5%5D+=+5