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Math and Science =>
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simonzack
Advanced Newbie
Joined: 25 Dec 2007
Posts: 71
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 Posted: 01 Jan 2008 11:47:15 pm Post subject: |
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proove that
n sigma k=1 (4/(k*(k+1)^2)* k sigma i=1 (i^2/a_i)<2* n sigma i=1 (i^2/a_i*( n sigma k=i (2k+1)/(k^2*(k+1)^2))
this is actually a part of another problem's solution, so i said it should'nt be hard...
Can anyone give a anwser |
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nitacku
Advanced Member
Joined: 23 Aug 2005
Posts: 408
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| Posted: 01 Jan 2008 11:59:03 pm Post subject: |
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I'm having trouble deciphering that equation.
Could you type it up using LaTex? |
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Weregoose
Authentic INTJ
Super Elite (Last Title)
Joined: 25 Nov 2004
Posts: 3976
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| Posted: 02 Jan 2008 01:58:42 am Post subject: |
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What you posted translates to...
...with a missing end parenthesis.
In requesting math help inside a forum, use proper notation. ;)
You may have meant (depending on the placement of the missing parenthesis):
Although, I'm really not sure what can be done with [font="courier new"]ai in there. Try again.
Last edited by Guest on 02 Jan 2008 02:06:14 am; edited 1 time in total |
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DarkerLine
ceci n'est pas une |
Super Elite (Last Title)
Joined: 04 Nov 2003
Posts: 8328
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| Posted: 02 Jan 2008 03:02:04 am Post subject: |
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| Well, by rearranging the LHS and switching the order of summation, you can get a similar sum as the RHS, but with the inner sum being [attachment=2069:attachment] rather than [attachment=2070:attachment]. Since the first fraction is obviously strictly less than the second, the entire sum works out as well. |
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simonzack
Advanced Newbie
Joined: 25 Dec 2007
Posts: 71
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| Posted: 02 Jan 2008 09:34:30 pm Post subject: |
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Thanks, I get it!
Is there anything to determine that 2 sigmas can be swapped?
ie when does {{i_1,k_1}...{i_n,k_n},sigma on left}={{i_1,k_1}...{i_n,k_n}, sigma on right}?
As in the format of maths, I will be more careful, sorry about bad syntax |
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