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Re: Solve...or not

  • To: mathgroup at smc.vnet.net
  • Subject: [mg128546] Re: Solve...or not
  • From: Bob Hanlon <hanlonr357 at gmail.com>
  • Date: Fri, 2 Nov 2012 00:45:06 -0400 (EDT)
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  • References: <20121101072008.AE953687B@smc.vnet.net>

$Version

"8.0 for Mac OS X x86 (64-bit) (October 5, 2011)"

eqns = {(y - 2)/(x - 1) == 1, y == 0};

Solve[eqns, {x, y}]

{{x -> -1, y -> 0}}

Solve[eqns, Variables[eqns]]

{{x -> -1, y -> 0}}

Simplify[Solve[eqns[[1]], x], eqns[[2]]]

{{x -> -1}}

Simplify[Solve[#[[1]], x], #[[2]]] &@eqns

{{x -> -1}}

Solve[eqns, x, Integers]

{{x -> ConditionalExpression[-1, y == 0]}}

Reduce[eqns, {x, y}] // ToRules

{x -> -1, y -> 0}

Reduce[eqns, x] // ToRules

{y -> 0, x -> -1}

Eliminate[eqns, y] // ToRules

{x -> -1}


Bob Hanlon


On Thu, Nov 1, 2012 at 3:20 AM, Harker, Anthony <a.harker at ucl.ac.uk> wrote:
>
> I've seen some discussion of Version 8's Solve[] in this group, but have I missed something explaining this?
>
>   I have the following behaviour (both under Windows 7)
>
>
> Mathematica 8.0.1.0
>
> Solve[{(y-2)/(x-1)==1,y==0},x]
> {}
>
> Mathematica 7.0.1.0
> Solve[{(y-2)/(x-1)==1,y==0},x]
> {{x->-1}}
>
>   Tony
>
> Tony Harker
> Department of Physics and Astronomy
> University College London
> Gower Street
> London
> WC1E 6BT
>
> Tel: (within UK)    020 7679 3404
>      (overseas ) +44 20 7679 3404
> E:    a.harker at ucl.ac.uk
>
> [...] clay possesses one considerable advantage: it is resistant to fire, water, and magnetic disturbances. In [...] a few thousand years, our photographs, books and hard disks will no doubt have disappeared, but our collections of cuneiform tablets will still be there.
>
>   Dominique Charpin, Reading and Writing in Babylon (2010) translated by Jane Marie Todd.



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