SOLUTION: if seventh term of geometric sequence is 64 and sum of first ten terms is 1023 then find the sum of fifteen terms of gs.
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Question 850701: if seventh term of geometric sequence is 64 and sum of first ten terms is 1023 then find the sum of fifteen terms of gs.
Answer by richwmiller(17219) (Show Source): You can put this solution on YOUR website!
Tn = t1 * r^(n - 1)
64 = t * r^(6)
Sum =t1*(1 - r^n)/(1 - r)
1023 = t*(1 - r^10)/(1 - r),
64 = t * r^(6)
r=2., t=1.
S =1*(1 - 2^15)/(1 - 2)
S = 32767
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