Re: Using Solve[] - What did I do wrong?

*To*: mathgroup at smc.vnet.net*Subject*: [mg109316] Re: Using Solve[] - What did I do wrong?*From*: Simon Pearce <Simon.Pearce at nottingham.ac.uk>*Date*: Wed, 21 Apr 2010 07:47:20 -0400 (EDT)*References*: <201004210830.EAA26548@smc.vnet.net>

Hi, You have four equations and effectively wish to solve for 5 variables, which Solve can't manage to do so it returns an empty solution set. If you only tell it to eliminate three of the four d variables then you get a solution which includes the last one. Simon -----Original Message----- From: eric948470 [mailto:eric948470 at gmail.com] Sent: 21 April 2010 09:31 To: mathgroup at smc.vnet.net Subject: [mg109316] [mg109305] Using Solve[] - What did I do wrong? Hi, If you look at the command below, you would probably be able to understand what I was trying to do. I have linear equations, and I want to solve for the variable g2, and I don't want the variables dx1, dx2, dy1 and dy2 in the answer. What I get for the output is {{}}. What did I do wrong? Solve[{phi2 + a2*dx1 + b2*dy1 + c2*dx2 + d2*dy2 == 0, psi2 + A2*dx1 + B2*dy1 + c2*dx2 + D2*dy2 == 0, dx2 == -g2 - = f2*dy2, dx1 == -g1 - f1*dy1}, g2, {dx1, dx2, dy1, dy2}] = This message has been checked for viruses but the contents of an attach= ment=0D=0Amay still contain software viruses which could damage your co= mputer system:=0D=0Ayou are advised to perform your own checks. Email c= ommunications with the=0D=0AUniversity of Nottingham may be monitored a= s permitted by UK legislation.=

**References**:**Using Solve[] - What did I do wrong?***From:*eric948470 <eric948470@gmail.com>