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What is ∑n=18(3n−1) equal to?

 

 May 17, 2018
 #1
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This is the sum of an arithmetic series

 

The first term  is   3(1)  - 1  = 2

The eighth term is 3(8)  - 1 = 23

 

The sum is

 

[first term + eigth term]  * number of terms  / 2  =

 

[ 2 + 23  ] * 8  / 2  =

 

[25] * 4  =

 

100

 

 

cool cool cool

 May 17, 2018

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