       simultaneous equations - eliminating variables and solving

• To: mathgroup at smc.vnet.net
• Subject: [mg100210] simultaneous equations - eliminating variables and solving
• From: nninja <not.a.ninja25 at gmail.com>
• Date: Thu, 28 May 2009 04:28:39 -0400 (EDT)

```Hi, I am a postgrad student and completely new to mathematica, I am just starting to realise the possibilities.

I am trying to do a chemical speciation calculation.
I have a set of simultaneous equations which represents the equilibria, mass balance, and charge balance in the system.

I want to eliminate some of the variables, and then be able to solve for the remaining ones.
My system of equations looks like this:
a=b+c+d
e=f+g+c+2d
h=c/(bg)
i=d/(cg)
hi=d/(bg^2)
j=mg/f
k=lm
n+m+b+c=g+l

This is what my formula looks like sofar.

Solve[{a == b + c + d, e == f + g + c + 2 d, h == c/(b*g),
i == d/(c*g), h*i == d/(b*g^2), j == m*g/f, k == l*m,
n + m + b + c == g + l}, {g}]

Basically, I can solve for the variable I want, but I am having trouble eliminating the ones I don't want (ie. I am getting an answer that is in terms of the wrong variables)

I have been in the help files for ages, and don't really understand how to do this.
I would really appreciate some pointers!!
Thanks

```

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