+0  
 
+1
253
1
avatar+272 

(-2)+1+4+7+...+55

YaBoiSpongebob  Apr 19, 2017
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 #1
avatar+79726 
+2

 

We have

 

-2 + 1 + 4 + 7 + .....+ 49 + 52 + 55   which can be written as

 

-2 + 55

1 + 52

4 + 49 .. etc...

 

So.....we have 20 terms ...... meaning  10 pairs that each sum to 53

 

So....10 * 53    =  530

 

 

cool cool cool

CPhill  Apr 19, 2017

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