?How do you find the sum of the infinite geometric series 4 + 3.2 + 2.56 + 2.048 + …?

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Answer 1 · 2016-01-02T17:04:30

First find the common ratio (r) and make sure the series is convergent (0 ≤ r ≤ 1)

r = #t_2/t_1#

r = #3.2/4#

r = 0.8

#S_∞# = #a/(1 - r)#

#S_∞# = #4 / (1 - 0.8)#

#S_∞# = 20

The series has a sum of 20