Re: System for which Solve and NSolve both fail

*To*: mathgroup at smc.vnet.net*Subject*: [mg30585] Re: System for which Solve and NSolve both fail*From*: David Reiss <dreissNOSPAM at DELETEscientificREMOVEMEarts.com>*Date*: Thu, 30 Aug 2001 03:51:31 -0400 (EDT)*Organization*: Scientific Arts*References*: <9mi1rt$54r$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Of course this is the same as : In[1]:= Solve[{3^x+3^(6-x) == 90},{x}] Out[1]= {{x -> 2},{x -> 4}} Which are your solutions... --David Ben Langton wrote: > Hi, > > I noticed that Mathematica seems unable to solve this system of equations : > > 3^x + 3^y = 90 > > x + y = 6 > > With a bit of thought, you can see by inspection that the solutions are > > {x , y} = {2 , 4} or {4 , 2} > > However, when I use the commands > > Solve[{3^x+3^y==90,x+y==6},{x,y}] > > or > > NSolve[{3^x+3^y==90,x+y==6},{x,y}] > > I get a warning message starting with > > Solve::incnst: Inconsistent or redundant transcendental equation > > Can anyone shed some light on what is going on here? Any way to get around > this problem? > > (I am using Mathematica v 3.0.0.0 under Mac OS 9.2.1, although I believe a > similar thing occurs under v 4.x) > > Regards, > > Ben Langton > > http://www.quickmath.com/