| Author |
Message |
comnint
Joined: 12 Oct 2004
Posts: 10
|
 13 Oct 2004 21:56 differential equations |
|
|
|
please help me for solve this differential equation
equation is in attach file[/img]
|
|
| Back to top |
|
 |
ihab
Joined: 03 Jul 2004
Posts: 28
|
| 06 Nov 2004 3:30 Re: differential equations |
|
|
|
| i tried doing my best still dont no how it may be solved????
|
|
| Back to top |
|
|
heo83
Joined: 07 Jul 2004
Posts: 29
Helped: 2
|
| 18 Nov 2004 8:07 differential equations |
|
|
|
Me, too.
At first, I thought this is just an ordinary diff equation, just like:
y' = y + x
But it's really a big problem when y' is in the denominator like this
1/y' = 1/y + 1/x
This diff equation does not have the form like any that I've learnt before. Maybe it's just because I don't know how to use sub-variable.
However, I think there are some diff equations having root that can not be expressed by normal functions that we've known.
Does anyone here know how to prove the root of this diff equation can not be expressed by normal functions like sin, cos, exponential, polynomical,...?
|
|
| Back to top |
|
|
nand_gates
Joined: 19 Jul 2004
Posts: 898
Helped: 117
|
| 22 Nov 2004 5:22 Re: differential equations |
|
|
|
I am also very much interested in solution of this differntial equation.
I also tried hard enough but no luck. It seems to be a nonlinear differntial
eq.
-nand_gates
|
|
| Back to top |
|
|
dazhen
Joined: 23 Nov 2004
Posts: 60
Helped: 2
Location: In the Mountain
|
| 24 Nov 2004 0:33 differential equations |
|
|
|
| I will suggest you to try Fourier transform. It may helps on the difficulty of 1/y'.
|
|
| Back to top |
|
|
nand_gates
Joined: 19 Jul 2004
Posts: 898
Helped: 117
|
| 24 Nov 2004 5:42 Re: differential equations |
|
|
|
| From where you got this differential eq. that may also help to solve it!
|
|
| Back to top |
|
|
gitarrelieber
Joined: 22 Apr 2003
Posts: 20
Helped: 2
|
| 06 Dec 2004 22:00 Re: differential equations |
|
|
|
| Differential equation whose solution satifies the existence and uniqueness can be solved by using Lie-algebra. The problem then is to find the suitable infinitesimal transformation which can be admitted by the equation itself. More information in the classic book "Symmetries and Differential Equations" G.W.Bluman, S.Kumei, Springer-Verlag 1989. A powerful package for Mathematica developed by Gerd Baumann is availabe in his book "Symmetry Analysis of Differential Equation with Mathematica".
|
|
| Back to top |
|
|
snaider
Joined: 08 Jul 2004
Posts: 145
Helped: 3
|
| 07 Dec 2004 3:26 Re: differential equations |
|
|
|
| you can always try to transform the differential equations , win fourier or laplace , quite always is the best way
|
|
| Back to top |
|
|
DrDolittle
Joined: 24 Sep 2004
Posts: 169
Helped: 4
Location: Within arm's reach
|
| 08 Dec 2004 8:55 Re: differential equations |
|
|
|
Please write the following in a sheet of paper for better understanding of the expressions
dy/dx = (x*y)/(x+y)
y' = dy/dx
so, (x*y')+(y*y') = (x*y)
y + (x*y')+(y*y') = y + (x*y)
d(xy)/dx + .5 d(y^2)/dx = y(1+x)
i/yd(xy) + [ (.5/y) d(y^2)] = (1+x)dx
I dont know what to do after this,perhaps this may be much use
Regards
drdolittle 
|
|
| Back to top |
|
|
