Re: differences in Solve with -1/2 and -0.5Re:

• To: mathgroup at smc.vnet.net
• Subject: [mg44401] Re: [mg44386] differences in Solve with -1/2 and -0.5Re:
• From: "Kenneth Levasseur" <Kenneth_Levasseur at uml.edu>
• Date: Sat, 8 Nov 2003 04:50:46 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```I'm using V4.2 on a Mac right now and I'm away from my office, so I
can't check my V5.  At least one of my students who is using
Mathematica for Students - V5, got the same "division by zero"
message.

KL

----- Original Message -----
From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
To: mathgroup at smc.vnet.net
Subject: [mg44401] Re: [mg44386] differences in Solve with -1/2  and -0.5

> On 7 Nov 2003, at 19:16, Kenneth Levasseur wrote:
>
> > Can anyone give a good reason why there is a difference in the
> > following?  Preferably one that my students will understand.
> >
> > In[1]:=
> > Solve[D[x E^(-x/2), x] == 0, x]
> > Out[1]=
> > {{x -> 2}}
> > In[2]:=
> > Solve[D[x E^(-0.5*x), x] == 0, x]
> > General::dbyz:Division by zero.
> > Out[2]=
> > {}
> >
> > Ken Levasseur
> > Math. Sciences
> > UMass Lowell
> >
> >
> >
>
> What version of Mathematica? In 5.0 I get:
>
> In[4]:=
> Solve[D[x E^(-x/2), x] == 0, x]
>
> Out[4]=
> {{x->2}}
>
> In[5]:=
> Solve[D[x E^(-0.5*x), x] == 0, x]
>
> Out[5]=
> {{x->2.}}
>
>
>
>
> Andrzej Kozlowski
> Yokohama, Japan
> http://www.mimuw.edu.pl/~akoz/
>
>
>
> E1-I: This message has been scanned for viruses and
dangerous
> content by UML's antivirus scanning services.
>
>
>
>

```

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