Re: Using Solve[] - What did I do wrong?

• To: mathgroup at smc.vnet.net
• Subject: [mg109321] Re: Using Solve[] - What did I do wrong?
• From: dh <dh at metrohm.com>
• Date: Wed, 21 Apr 2010 07:48:15 -0400 (EDT)
• References: <hqmd3t\$pti\$1@smc.vnet.net>

```On 21.04.2010 10:30, eric948470 wrote:
> Hi,
>
> If you look at the command below, you would probably be able to
> understand what I was trying to do. I have linear equations, and I
> want to solve for the variable g2, and I don't want the variables dx1,
> dx2, dy1 and dy2 in the answer. What I get for the output is {{}}.
> What did I do wrong?
>
> Solve[{phi2 + a2*dx1 + b2*dy1 + c2*dx2 + d2*dy2 == 0,
>    psi2 + A2*dx1 + B2*dy1 + c2*dx2 + D2*dy2 == 0, dx2 == -g2 - f2*dy2,
>    dx1 == -g1 - f1*dy1}, g2, {dx1, dx2, dy1, dy2}]
>
Hi,
every elimination of a variable "eats up" one equation. Therefore, you
need 5 equations to eliminate 4 variables and solve for g2.
cheers, Daniel

--

Daniel Huber
Metrohm Ltd.
Oberdorfstr. 68
CH-9100 Herisau
Tel. +41 71 353 8585, Fax +41 71 353 8907
E-Mail:<mailto:dh at metrohm.com>
Internet:<http://www.metrohm.com>

```

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