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MathGroup Archive 2005

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Re: Form of a linear equation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg53741] Re: [mg53734] Form of a linear equation
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Wed, 26 Jan 2005 04:36:15 -0500 (EST)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

eqn=-(4+4x+y)/17^(1/2)\[Equal](2+x+y)/2^(1/2);

eqn /. (lhs_==rhs_):>(Collect[lhs-rhs,{x,y}]==0)

(-(1/Sqrt[2]) - 4/Sqrt[17])*x + 
   (-(1/Sqrt[2]) - 1/Sqrt[17])*y - 4/Sqrt[17] - 
   Sqrt[2] == 0

eqn /. (lhs_==rhs_):>(Collect[lhs-rhs,{x,y},Together]==0)

(1/34)*(-17*Sqrt[2] - 8*Sqrt[17])*x + 
   (1/34)*(-17*Sqrt[2] - 2*Sqrt[17])*y + 
   (1/17)*(-17*Sqrt[2] - 4*Sqrt[17]) == 0


Bob Hanlon

> 
> From: "DJ Craig" <spit at djtricities.com>
To: mathgroup at smc.vnet.net
> Date: 2005/01/25 Tue AM 05:03:48 EST
> To: mathgroup at smc.vnet.net
> Subject: [mg53741] [mg53734] Form of a linear equation
> 
> I'm trying to convert this linear equation:
> 
> -(4+4x+y) / 17^(1/2) = (2+x+y) / 2^(1/2)
> 
> into the form:
> 
> (a_)*x + (b_)*y + (c_) = 0
> 
> This sounds simple enough, but I can't figure out how to make
> Mathematica do it.  My TI-89 does it automatically, but I need to be
> able to do this like a batch process for a bunch of linear equations.
> Heres the solution the TI-89 gives me:
> 
> \!\(\*
> StyleBox[\(\((\(\(-4\)\ \@17\)\/17 - \@2\/2)\)\ x + \((\(-\@17\)\/17
> - \
> \@2\/2)\)\ y - \(3\ \@17\)\/17 - \@2 = 0\),
> FontWeight->"Bold"]\)
> 
> Just copy and paste that mess into Mathematica and it will change into
> the equation at the top, but in the form that I want it.
> 
> I haven't been using Mathematica for long.  I'm used to my TI-89; I've
> been using it for years.
> 
> 


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