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What is the sum of the first 47 terms of the sequence?

−215,−201,−187,−173,...

 May 27, 2019

Best Answer 

 #1
avatar+18274 
+2

This is an ARITHMETIC series with common difference, d = 14     a1 = -215

a47 = a1 + (47-1)(14)

       = -215 + 46(14) = 429

 

S47 = n(a1+a47)/2 = 47(-215 +429)/2 = 5029

 May 28, 2019
edited by ElectricPavlov  May 28, 2019
 #1
avatar+18274 
+2
Best Answer

This is an ARITHMETIC series with common difference, d = 14     a1 = -215

a47 = a1 + (47-1)(14)

       = -215 + 46(14) = 429

 

S47 = n(a1+a47)/2 = 47(-215 +429)/2 = 5029

ElectricPavlov May 28, 2019
edited by ElectricPavlov  May 28, 2019

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