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Re: Different (real) solutions using Solve for same equation ?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg101872] Re: Different (real) solutions using Solve for same equation ?
  • From: Richard Fateman <fateman at cs.berkeley.edu>
  • Date: Mon, 20 Jul 2009 06:02:00 -0400 (EDT)
  • References: <h3uv8v$kck$1@smc.vnet.net>

Bill Rowe wrote:
>...


> 
> That is the re-write you did implicitly assumes certain values
> are not zero. Mathematica never makes such assumptions.

Not in my experience. It makes such assumptions in many instances.  The 
simplest one that comes to mind is this.


Solve[(x-a)/(x-b)==0,x]   produces x -->a.  Using Reduce reminds you 
that a-b had better not be zero.

So Solve assumes a-b is not zero.

another:

Integrate[x^n,x]

assumes n+1 is not zero.

Even the documentation says
"Parameters like n are assumed to be generic inside indefinite integrals."


RJF


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