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MathGroup Archive 2006

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Re: solve differential equation problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg68840] Re: solve differential equation problem
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Mon, 21 Aug 2006 03:27:35 -0400 (EDT)
  • Organization: The Open University, Milton Keynes, UK
  • References: <ec97dc$4b3$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

elvis wrote:
> Here we often use mathematica to solve differential equations, when I
> encouter a equation with several constrains I set them to those values.
> But it cannot solve it and have the following warnings:
> 
>     DSolve::deqx: Supplied equations are not differential equations of
> the given functions.
> 
> Give a very simple differential equation here:
> 
>   DSolve[{y'[x] == r*y[x], y[0] == a}, y, x]
> 
> Can anyone help to "solve" this problem for me?
> Thanks!
> 

Some of the symbols y, x, r, a must have been define to some values 
before you try to solve your differential equation. Restart the kernel 
or start a fresh session and try again. I had no problem on my system:

DSolve[{Derivative[1][y][x] == r*y[x], y[0] == a}, y, x]

--> {{y -> Function[{x}, a*E^(r*x)]}}

HTH,
Jean-Marc


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