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Student Support Forum: 'Help - Derivative of Sums' topicStudent Support Forum > General > "Help - Derivative of Sums"

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10/14/10 8:00pm

In Response To 'Re: Help - Derivative of Sums'
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I think I now understand what is happening here.

The Sum of D[Subscript[xm,i],Subscript[xm,i]] is expanded and cancels the k.

D[1/k Sum(i = 1,k) Subscript[xm,i],] ==
1/k Sum(i = 1,k) D[Subscript[xm,i],] ==
(1/k) (1+1+1..1) ==
(1/k) (k*1) ==
1

The lower-case L from the xw Sum is still in the numerator.


The attached notebook has an expanded version.

Attachment: stu23594problemC.nb, URL: ,

Subject (listing for 'Help - Derivative of Sums')
Author Date Posted
Help - Derivative of Sums Gruber 09/27/10 02:27am
Re: Help - Derivative of Sums Forum Modera... 09/27/10 1:22pm
Re: Help - Derivative of Sums Gruber 09/28/10 02:32am
Re: Re: Help - Derivative of Sums Forum Modera... 10/14/10 8:00pm
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