System for which Solve and NSolve both fail
- To: mathgroup at smc.vnet.net
- Subject: [mg30572] System for which Solve and NSolve both fail
- From: Ben Langton <ben at spam.bugs.me.quickmath.com>
- Date: Wed, 29 Aug 2001 01:40:17 -0400 (EDT)
- Organization: OzEmail Ltd, Australia
- Sender: owner-wri-mathgroup at wolfram.com
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/