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Express the sum 10 + 11 + 12 + ... + n in terms of n.

 Dec 13, 2020
 #1
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Sum = 

 

[ First term + Last term ]   ( Number of Terms ) / 2

 

   [ 10 + n ]  * ( n - 10 + 1)  / 2  = 

 

[ 10 + n ]  *  ( n - 9)  / 2

 

 

cool cool cool

 Dec 13, 2020

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