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if the first term of a gp is 6 ans the sum of first 15 terms is 29. find the common ratio of the gp?

if the first term of a gp is 6 ans the sum of first 15 terms is 29. find the common ratio of the gp?

Grade:12

4 Answers

ng29
1698 Points
8 years ago
=i think its quite easy , u can use the formula of sum of terms of gp
commom terms is known and sum of 15 terms are also given
put data in formula and get value of common ratio
 
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sudhir
10 Points
8 years ago
Hi ng29,
if we use the sum of n terms formula we get 
29=6(r^15-1)/r-1
=> 6r^15 -29r – 23=0
now , how to get the value of r from here?
plz. guide 
Thank you
ng29
1698 Points
8 years ago
ok i understand that whats ur doubt
equation of such higher degree is impossible to solve
so method for this is hit and trial
on putting  r =  -1  , condition is satisfied , hence the answer
 
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APPROVE IF USEFUL
sudhir
10 Points
8 years ago
Hi, Thanks for your help...Is ther

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