Hi

sum of the first two terms is 15 for a geometric series

, where r is the common ratio











 

 27 = 15/(1-r^2)

1-r^2 = 15/27

   r^2 = 12/27 = 4/9

   r = 2/3 sequence has all positive terms..tossing out negative solution for r



(b) The first term;

 

 

 

   

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