How would you expand the double summation:

I understand that:

Gets you something like:

and

is

But how can you combine these two? Is it as simple as foiling the entire thing?

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- Mar 23rd 2010, 05:10 PMvlai9180Double Summations
How would you expand the double summation:

I understand that:

Gets you something like:

and

is

But how can you combine these two? Is it as simple as foiling the entire thing? - Mar 24th 2010, 12:03 AMHaven
If you're familiar with programming, double summations work like nested for loops. Ever time we iterate the outer summation, we run the entire inner summation. So every time i increases by 1, we go through all the possible values of j. In this case, every time i increases, we sum j from 1 to 2.

So - Mar 24th 2010, 12:12 AMmr fantastic
Also asked and answered here: http://www.mathhelpforum.com/math-he...ummations.html

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