differences in Solve with -1/2 and -0.5

*To*: mathgroup at smc.vnet.net*Subject*: [mg44386] differences in Solve with -1/2 and -0.5*From*: "Kenneth Levasseur" <Kenneth_Levasseur at uml.edu>*Date*: Fri, 7 Nov 2003 05:16:43 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

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

**Follow-Ups**:**Re: differences in Solve with -1/2 and -0.5***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>