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#1 Re: Help Me ! » positive integral solution. » 2007-08-29 05:16:36

Yeah it would be useful if someone explains what a positive integral solution is.

#2 Re: Help Me ! » Plotting a function » 2007-07-23 02:56:19

Actually I did a research abou this myself and I found out in a physical chemistry book that logarithmic equations such as the above are called "transcendental equations", equations that do not have a solution in a closed form. The solutions are rather found using a mathematical software. I had that in mind although I thought there could be some sort of a mathematical trick or something that can be applied.


Oren

#3 Re: Help Me ! » Definite integral » 2007-07-21 09:20:29

I = ∫ [ 1 / ( 1 + cosx ) ( 1 + cosx) ] dx

t = 1 / 1 + cosx

dt = [ sinx / ( 1 + cosx)( 1 + cosx) ] dx

Cosx = 1 / t - 1 so Sinx = sqrt [( 2t - 1 / t )] / t

I = ∫ [ t / sqrt( 2t -1 ) ] dt  = 1/2 ∫ [ ( 2t +1 - 1 ) / sqrt(2t - 1 ) ] dt

I = 1 / 2  ∫ [ sqrt ( 2t -1 ) - 1 / sqrt ( 2t - 1 ) ] dt

I = 1 /2 sqrt(2t -1)  [ ( 2t -1 ) / 3 - 1 ]

If im not mistaken the final expression should be something like this :

I = 1 /2 sqrt ( 1 - Cosx / 1 + Cosx ) [ (1 /3) (1 - Cosx) / ( 1 + Cosx ) - 1 ] + C

The definite integral can then be evaluated. Sorry for this unclearness as I still havent learned about LAtex

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