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what is the sum of the first 10 terms of the sequence defined by ^an=2n-3?

 Jul 9, 2015

Best Answer 

 #1
avatar+102320 
+5

I assume we have   .....

                                                                   

an = 2n -3 

 

The first term =a1 =  2(1)-3   = -1

 

And the 10th term = a10 = 2(10) - 3 = 20 - 3 = 17    

 

And the sum of the first 10 terms =  10(a1 + a10)/2  =   10(-1 + 17)/2 = 5(16)  = 80

 

 

  

 Jul 9, 2015
 #1
avatar+102320 
+5
Best Answer

I assume we have   .....

                                                                   

an = 2n -3 

 

The first term =a1 =  2(1)-3   = -1

 

And the 10th term = a10 = 2(10) - 3 = 20 - 3 = 17    

 

And the sum of the first 10 terms =  10(a1 + a10)/2  =   10(-1 + 17)/2 = 5(16)  = 80

 

 

  

CPhill Jul 9, 2015

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