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Re: Solving simultaneous eqns
*To*: mathgroup at smc.vnet.net
*Subject*: [mg14285] Re: [mg14199] Solving simultaneous eqns
*From*: Jurgen Tischer <jtischer at col2.telecom.com.co>
*Date*: Mon, 12 Oct 1998 13:52:02 -0400
*Sender*: owner-wri-mathgroup at wolfram.com
Hi Yun,
I have tried to solve your equations, but my solution is not very
convincing. I add the notebook anyway.
Jurgen
Yeoung-Sang Yun wrote:
> Hello!
>
> I want to know how to solve the following simulaneous equations in
> Mathematica:
>
> x=x^1.2/(2*x^3+y^0.7+4*z^2.5)
> y=y^0.7/(2*x^0.6+y^2+z^2.2)
> z=0.9*z^1.5/(x^0.7+2*y^0.2+z^1.1)
>
> Thanks for helping.
> Y.-S. Yun
> Department of Chemical Engineering
> Pohang University of Science and Technology San 31, Hyoja-dong, Pohang
> 790-784, Republic of Korea
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Cell["\<\
To facilitate writing for me I changed the equations to a function whose
\ zeros are the solutions of your problem. \ \>", "Text"],
Cell[BoxData[
\(f[x_, y_, z_] = {x - x\^1.2\/\(2\ x\^3 + y\^0.7 + 4\ z\^2.5\),
y - y\^0.7\/\(2\ x\^0.6 + y\^2 + z\^2.2\),
z - \(0.9\ z\^1.5\)\/\(x\^0.7 + 2\ y\^0.2 + z\^1.1\)}\)],
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First I observe that for every two variables zero I can calculate a
solution.\ \
\>", "Text"],
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Now I'm just searching around with FindRoot. (I checked with much more \
values, this is just the result.)\
\>", "Text"],
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" I start having the idea there are no other solutions with
z\[NotEqual]0 \ than the one already found. Now if ",
Cell[BoxData[
\(TraditionalForm\`z == 0\)]],
", the third equation is satisfied, so to look for posible solutions I
look \ at the intersections of the zeros of the first and the second
equation and \ find there are two solutions, the two I found already."
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"To see what happens for ",
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"Looks like there is no solution for ",
Cell[BoxData[
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