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November 18th, 2009, 08:15 PM   #1
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Sigma Simplification

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November 19th, 2009, 05:47 AM   #2
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What concept? Why would you try to apply a concept based on the first example (especially one that you merely "kind of understand") to the second instead of the other way round?
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November 19th, 2009, 04:44 PM   #3
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Re: Sigma Simplification

The manipulation of example 2 has an error. When you went from i+1 to i inside the summation, you needed to change the lower limit from 1 to 2.
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November 20th, 2009, 11:45 AM   #4
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Re: Sigma Simplification

But why didn't I need to change the lower limit in example 1 from 1 to 0?
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November 20th, 2009, 11:49 AM   #5
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Re:

Quote:
Originally Posted by skipjack
What concept? Why would you try to apply a concept based on the first example (especially one that you merely "kind of understand") to the second instead of the other way round?
Well in example 2 I need to bring the lower limit to 1 right? Which then gave me 5(i+1) for the summation. Now in example 1 I cleared the parenthesis by manipulating the upper limit so I tried that same concept in example 2 to clear the parenthesis.
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November 20th, 2009, 02:27 PM   #6
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Re: Sigma Simplification

Quote:
Originally Posted by David_Lete
But why didn't I need to change the lower limit in example 1 from 1 to 0?
Strictly speaking you should (in general). However in this case the i=0 term =0, so it didn't matter that it was left out.
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November 21st, 2009, 02:52 PM   #7
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Re: Sigma Simplification

In your first example, the last sum actually begins i=0, not 1. But of course for the term i^2 it didn't matter that you leave that term out.
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