Re: Please explain this weird Integrate result

*To*: mathgroup at smc.vnet.net*Subject*: [mg60142] Re: Please explain this weird Integrate result*From*: "Scout" <not at nothing.net>*Date*: Sun, 4 Sep 2005 03:02:05 -0400 (EDT)*References*: <dfbevv$inu$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

"Jose Reckoner" <reckoner at gmail.com> > > Expand[Integrate[(2*x)/(2*x - 1), x]] > > gives > > -1/2 + x + Log[-1 + 2*x]/2 > > But, > > Expand[Integrate[1 + 1/(-1 + 2*x), x]] > > gives > > x + Log[-1 + 2*x]/2 > > even though > > (2*x)/(2*x - 1) == 1 + 1/(-1 + 2*x) > > Where did the extra -1/2 in the first result come from? > Hi Jose, I don't know why you've obtained these different (and incorrect) results on the same integral! Maybe some pre-assignements on x? (Clear[] will help you ;-) ) On my system (Math.4) it gives: In[1]:= a=Expand[Integrate[(2*x)/(2*x - 1), x]]; In[2]:= b=Expand[Integrate[1 + 1/(-1 + 2*x), x]]; In[3]:= a==b Out[3]= True In[4]:= a Out[4]= x + Log[-1+2 x] / 2 ~Scout~