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What is the smallest integer that can possibly be the sum of an infinite geometric series whose first term is 9?

 

Please explain very well in this question.

 Jan 24, 2015

Best Answer 

 #1
avatar+17747 
+11

The formula for the sum of an infinite series is:  Sum  =  a/(1 - r) provided that -1 < r <  1.

As r gets closer and closer to -1, the sum gets closer and closer to 4.5; so x can be 5 (if r = -4/5).

 Jan 24, 2015
 #1
avatar+17747 
+11
Best Answer

The formula for the sum of an infinite series is:  Sum  =  a/(1 - r) provided that -1 < r <  1.

As r gets closer and closer to -1, the sum gets closer and closer to 4.5; so x can be 5 (if r = -4/5).

geno3141 Jan 24, 2015
 #2
avatar+95360 
+5

Thanks Geno, 

I had to think about that one!   

 Jan 25, 2015

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