+0  
 
+1
55
2
avatar+293 

i don't know what to do.

 Dec 2, 2020
 #1
avatar
+1

Go to this link and learn how to  use the Summation Calculator. I have already entered your problem into the calculator and see the answer at the bottom (10,600):

 

https://www.mathsisfun.com/numbers/sigma-calculator.html

 Dec 2, 2020
 #2
avatar+114592 
+1

This is an arithmetic series   (AS)

 

First term  =  2(1)  +  5   = 7

Last term    = 2(100) + 5 =  205

 

Sum  of  an  AS   =   [ first term + last term ]  * number of terms   / 2   ....so we  have....

 

[  7  +  205 ]  (100 )  /  2   =

 

[ 212] * 50   =

 

10600 

 

 

cool cool cool

 Dec 2, 2020

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