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The sum of the first n terms in the infinite geometric sequence {14,18,116,}  is 255512 . Find  n.

 Dec 30, 2017
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We have that

 

255/512  =  (1/4) [  1 - (1/2)^n  ]  /  [  1 - 1/2]    simplify

 

255/512 =  (1/2) [ 1 - (1/2)^n ]  

 

255 / 256 =  1 - (1/2)^n

 

(1/2)^n  =   1 -  255/256

 

(1/2)^n  =  1/256

 

(1/2)^n  =  (1/2)^8

 

So....n  = 8

 

 

cool cool cool

 Dec 30, 2017

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