The sum of an infinite geometric series is 125, and the value of r is 0.4. How do you find the first three terms of the series?

1 Answer
Noah G
Nov 13, 2016

The first three terms are #75, 30, 12#.

Explanation:

The formula for sum of an infinite, convergent geometric series is #s_oo = a/(1- r)#, where #s_oo# is the sum, #a# is the first term of the series and #r# is the common ratio.

Hence,

#125 = a/(1 - 0.4)#

#125 xx 0.6 = a#

#a = 75#

We know that #r = 0.4#, so:

#t_2 = 75 xx 0.4 = 30#

#t_3 = 30 xx 0.4 = 12#

Hopefully this helps!

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