SOLUTION: 1) determine the sum of the arithmetic series 19.5+14+8.5+...t24 2)Determine the value of t1 for an arithmetic sequence, where d=-4 and S14 = 1120

Algebra ->  Sequences-and-series -> SOLUTION: 1) determine the sum of the arithmetic series 19.5+14+8.5+...t24 2)Determine the value of t1 for an arithmetic sequence, where d=-4 and S14 = 1120      Log On


   

Question 1086467: 1) determine the sum of the arithmetic series 19.5+14+8.5+...t24
2)Determine the value of t1 for an arithmetic sequence, where d=-4 and S14 = 1120
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
1) determine the sum of the arithmetic series 19.5+14+8.5+...t24
t2-t1 = 14-19.5 = -5.5 = d
t3-t2 =  8.5-14 = -5.5 = d

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

Substitute n = 24, t1 = 19.5, and d = -5.5,
to find S24

2)Determine the value of t1 for an arithmetic sequence,
where d=-4 and S14 = 1120
S%5Bn%5D=expr%28n%2F2%29%282t%5B1%5D%2B%28n-1%29d%29

Substitute n = 14, d = -4, then substitute S14 = 1120. 

Then solve for t1.

Edwin