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Student Support Forum: 'Simple question. How to solve equations system.' topicStudent Support Forum > General > "Simple question. How to solve equations system."

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Ilya
06/10/04 07:03am

Hello all,

I am in a clinch with the following problem. I am trying to solve simple optimization problem using Mathematica:

The function is
Y=Y(x1,x2) = Exp[-x1a1S1 - x2a2s2]q1q2 + Exp[-x1a1s1 - x2b2S2] + Exp[-x1b1s1-x2a2s2] + Exp[-x1b1s1-x2b2s2]. Where xi, ai, si, pi - constants.

To find the infinum one have to solve system of equations dY/dx1=0, dY/dx2=0.

The most rediculus point is that I can solve it manually with simple substitution but the Great Mathematica returns me the error: "The equations appear to involve the variables to be solved for in an essentially non-algebraic way." How can it be?

Could you please help me to solve this puzzle? How to solve this system in Mathematica!!!??? Supporting code would be greately appretiated!

Here is the code I use (with slight different and more attractive notation then I used above). Just copy and paste it in your wolfram software:

\!\(SetAttributes[{a\_1, a\_2, b\_1, b\_2, S\_1, S\_\(\(2\)\(\ \)\), \ q\_1,
q\_2, \ p\_1, p\_2, \ A, B, C, D}, \ Constant]\[IndentingNewLine]
Y\ = \ Exp[\(-\[Gamma]\_1\) \(a\_1\) S\_1 - \ \(\[Gamma]\_2\) \(a\_2\)
S\_2] \(q\_1\) q\_\(\(2\)\(\ \)\) + \
Exp[\(-\[Gamma]\_1\) \(a\_1\) S\_1 - \ \(\[Gamma]\_2\) \(b\_2\)
S\_2]\ \(q\_1\) p\_2\ + \
Exp[\(-\[Gamma]\_1\) \(b\_1\) S\_1 - \ \(\[Gamma]\_2\) \(a\_2\)
S\_2] \(p\_1\) q\_2\ + \
Exp[\(-\[Gamma]\_1\) \(b\_1\) S\_1 - \ \(\[Gamma]\_2\) \(b\_2\)
S\_2]\ \(p\_1\) p\_\(\(2\)\(\ \)\)\[IndentingNewLine]
Solve[{D[Y, \[Gamma]\_1] == 0, \
D[Y, \[Gamma]\_2] ==
0}, {\[Gamma]\_2, \[Gamma]\_1}\ ]\ /; \ {\(p\_1\)
b\_1/\((\(q\_1\) a\_1)\) == 1\ }\)

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Subject (listing for 'Simple question. How to solve equations system.')
Author Date Posted
Simple question. How to solve equations system. Ilya 06/10/04 07:03am
Re: Simple question. How to solve equations sys... Henry Lamb 06/16/04 2:50pm
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