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Re: Different cases in Solve

• To: mathgroup at smc.vnet.net
• Subject: [mg89608] Re: Different cases in Solve
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Sat, 14 Jun 2008 05:31:50 -0400 (EDT)
• Organization: The Open University, Milton Keynes, UK
• References: <g2th6g$7kr$1@smc.vnet.net>

Aaron Fude wrote:

> When one does Solve[a x == b, x], one gets {{x -> b/a}}. How does one
> get Mathematica to give you different solutions depending on cases: b/
> a if a nonzero, any number if a==b==0, and no solutions if a=0 and b
> is nonzero?

The online help reads, "Solve gives generic solutions only. It discards 
solutions that are valid only when the parameters satisfy special 
conditions. Reduce gives the complete set of solutions." Therefore,


In[1]:= Reduce[a x == b, x]

Out[1]=
                                       b
(b == 0 && a == 0) || (a != 0 && x == -)
                                       a


Regards,
-- Jean-Marc