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The sum of the first terms n in the infinite geometric sequence {1/4, 1/8, 1/16, ..} is 15/32. Find  n.

 Jun 10, 2021
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a = 1/4 (first term)

r = 1/2 (ratio)

n = number of terms

 

15/32 = 1/4((1/2)^n - 1)/(1/2 - 1)

Try to solve it by yourself from here. :))

 

 

15/32 = 1/4((1/2)^n - 1)/(1/2 - 1)

15/8 = ((1/2)^n - 1)/(-1/2)

-15/16 = (1/2)^n - 1

1/16 = (1/2)^n

n = 4

 

=^._.^=

 Jun 10, 2021

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