SOLUTION: I got stuck in this problem can someone please help me Thanks in advance ☺ Find tn for the following geometric sequence -60,30.-15,.... then use tn to find t20

Algebra ->  Sequences-and-series -> SOLUTION: I got stuck in this problem can someone please help me Thanks in advance ☺ Find tn for the following geometric sequence -60,30.-15,.... then use tn to find t20      Log On


   

Question 1022736: I got stuck in this problem can someone please help me
Thanks in advance ☺
Find tn for the following geometric sequence -60,30.-15,.... then use tn to find t20
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
t%5Bn%5D+=+t%5B1%5D%2Ar%5E%28n-1%29 ==> t%5Bn%5D+=+-60%2A%28-1%2F2%29%5E%28n-1%29
==> t%5B20%5D+=+-60%2A%28-1%2F2%29%5E19+=+15%2F2%5E17+=+15%2F131072, or 0.00011444 to eight decimal places.