SOLUTION: Find the fifth term of a geometric sequence whose fourth term is 16/27 and whose seventh term is 128/729.

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Question 851136: Find the fifth term of a geometric sequence whose fourth term is

16/27 and whose seventh term is 128/729.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi,

a%5Bn%5D+=+a%5B1%5Dr%5E%28n-1%29+

a%5B4%5D+=+a%5B1%5Dr%5E3+=+16%2F27 , a%5B1%5D+=+16%2F27r%5E3

a%5B7%5D+=+%2816%2F27r%5E3%29r%5E6+=+128%2F729  r%5E3+=+%28128%2F729%29%2827%2F16%29   r = 2/3

 a%5B1%5D+=+16%2F%28%2827%29%288%2F27%29%29+=+2+

a%5B5%5D+=+2%282%2F3%29%5E4+=+32%2F81