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Algebra

Blazing goIITian

Joined:	25 Jul 2011
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27 Mar 2012 09:30:43 IST

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443

Tough one! lets c who can do it !

Engineering Entrance , JEE Main , JEE Advanced , Mathematics , Algebra

Find the value of the sum:
$\frac{1}{1+2} + \frac{2}{1+2+3} +\frac{3}{1+2+3+4 }+......+\frac{2011}{1+2+3+4+....+2010+2011}$

Comments (11)

hemang

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27 Mar 2012 10:44:06 IST

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no simple method to do it..

i don't understand a word of it..

copied it from wolfram alpha so that people don't waste their time on this question.

srinivasan

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27 Mar 2012 11:22:26 IST

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macha .. best is calculus approach :)

srinivasan

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27 Mar 2012 11:27:54 IST

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2010/2011 ??? ?? ??

srinivasan

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27 Mar 2012 11:29:55 IST

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@ hemang -- what is wolfram alpha

santanu sinha

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27 Mar 2012 11:33:01 IST

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no man! the first four terms sum up to get something more than 2010/2011

sathyaram

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27 Mar 2012 12:28:30 IST

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@ srinivasan: MAcha,its a calculating engine which express the no. For ex,u eant to find the reminder when 2^44 is divided by 4,u csn paste it on the wolfram website,It will actually be,refer this linkle to find out...http://www.wolframalpha.com/input/?i=2%5E44+mod+3

srinivasan

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27 Mar 2012 12:55:45 IST

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@sathya - thanks machi its nice website :)

boywholived

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27 Mar 2012 14:19:47 IST

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while solving i am getting two harmonic progression's which sum is impossible to exactly calculate.

sathyaram

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27 Mar 2012 20:00:54 IST

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$$ The answer for this question is :$

$2\sum_{k=1}^{n+2} \frac {1} {k} - 4 + \frac {2} {n+2}$

boywholived

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28 Mar 2012 14:51:58 IST

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@satyaram it is a harmonic series and couldn't be summed.

pooja garg

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28 Mar 2012 14:58:26 IST

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plz explain how it could b solved

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