SOLUTION: Find the first term and the common difference for the arithmetic sequence. Round approximations to the nearest hundredth S3 = 33, a3 = 15 show work

Algebra ->  Sequences-and-series -> SOLUTION: Find the first term and the common difference for the arithmetic sequence. Round approximations to the nearest hundredth S3 = 33, a3 = 15 show work      Log On


   

Question 475307: Find the first term and the common difference for the arithmetic sequence. Round approximations to the nearest hundredth
S3 = 33, a3 = 15 show work
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
S%5B3%5D=++33+=+%28n%2F2%29%28a%5B1%5D+%2B+a%5Bn%5D%29+=+%283%2F2%29%28a%5B1%5D+%2B+15%29
==> 33+=+%283%2F2%29%28a%5B1%5D+%2B+15%29 ==> 22+=+a%5B1%5D+%2B+15 ==> a%5B1%5D+=+7
Now 15+=+a%5B3%5D+=+a%5B1%5D+%2B+2d+=+7+%2B+2d
==> 7 + 2d = 15, or 2d = 8, or d = 4.