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

*To*: mathgroup at smc.vnet.net*Subject*: [mg44398] Re: [mg44386] differences in Solve with -1/2 and -0.5*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Sat, 8 Nov 2003 04:50:43 -0500 (EST)*References*: <200311071016.FAA05493@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

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/

**References**:**differences in Solve with -1/2 and -0.5***From:*"Kenneth Levasseur" <Kenneth_Levasseur@uml.edu>