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What is ∑n=16[4(−5)n−1]∑n=16[4(−5)n−1] equal to?

 

 May 17, 2018
 #1
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This  will be the sum of a geometric series where the first term is 4

The common ratio  is -5

And we will have 6 terms.....so....the sum is

 

first term   [ 1  -  common ratio^number of terms ] / [ 1 - common ratio ]  =

 

4  [1 - (-5)^6]  /  [ 1  - -5 ]  =

 

4 [ 1 - 15625 ] / 6  =

 

(2/3) ( -15624 )  =

 

-10416

 

 

 

cool cool cool

 May 17, 2018

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