SOLUTION: find first term of a geometric sequence whose fifth term and eighth term are 405 and 10935 respectively.

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Question 978581: find first term of a geometric sequence whose fifth term and eighth term are 405 and 10935 respectively.
























Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
That is three ratio's worth, for a variable r.

10935%2F405=r%5E3 and then work from index 5 downward to index 1.
r%5E3=27.
r=3.

Going from the term number 5 to the term number 1 is a change by four of the common ratio. Can you find this?