Re: Equation solving problem

• To: mathgroup at smc.vnet.net
• Subject: [mg125060] Re: Equation solving problem
• From: Juhász Péter <juhaszp.piarhf at gmail.com>
• Date: Mon, 20 Feb 2012 02:47:04 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <jhqmm3\$fae\$1@smc.vnet.net>

```On Feb 19, 12:33 pm, Juh=E1sz P=E9ter <juhaszp.pia... at gmail.com> wrote:
> I have the following problem: I would like to solve a set of 3
> equations, but Mathematica's solution involves unknown variables. My
> input was:
>
> Solve[{nc^2/Sqrt[1 - v^2/c^2] == mc^2/Sqrt[1 - b^2/c^2] + pc,
>   nv/Sqrt[1 - v^2/c^2] == (mb Cos[\[Alpha]])/Sqrt[1 - b^2/c^2] +
>     p Sin[\[Alpha]], (mb Sin[\[Alpha]])/Sqrt[1 - b^2/c^2] ==
>    p Cos[\[Alpha]]}, {v, b, p}]
>
> And the output started like:
>
> {{v -> -(I c \[Sqrt](mc^4 nv^2 Cos[\[Alpha]]^2 -
>           2 mb mc^2 nc^2 nv Cos[\[Alpha]]^3 +
>           mb^2 nc^4 Cos[\[Alpha]]^4 - mb^2 pc^2 Cos[\[Alpha]]^4=
-
>           2 mb mc^2 nc^2 nv Cos[\[Alpha]] Sin[\[Alpha]]^2 +
>           2 mb^2 nc^4 Cos[\[Alpha]]^2 Sin[\[Alpha]]^2 -
>           2 mb^2 pc^2 Cos[\[Alpha]]^2 Sin[\[Alpha]]^2 +
>           mb^2 nc^4 Sin[\[Alpha]]^4 -
>           mb^2 pc^2 Sin[\[Alpha]]^4))/(mb pc Sqrt[
>        Cos[\[Alpha]]^4 + 2 Cos[\[Alpha]]^2 Sin[\[Alpha]]^2 +
>         Sin[\[Alpha]]^4]),
>   b -> -1/(nv pc) (\[Sqrt](-c^2 mc^4 nv^2 + c^2 nv^2 pc^2 +
>          2 c^2 mb mc^2 nc^2 nv Cos[\[Alpha]] -
>          c^2 mb^2 nc^4 Cos[\[Alpha]]^2 -
>          2 c^2 mb^2 nc^4 Sin[\[Alpha]]^2 +
>          2 c^2 mb mc^2 nc^2 nv Sin[\[Alpha]] Tan[\[Alpha]] -
>          c^2 mb^2 nc^4 Sin[\[Alpha]]^2 Tan[\[Alpha]]^2)),
>          .... .... ....
>
> And so on. It is clear, that if we look at the solution for v, it
> involves unknowns b and p. If anyone could tell me what I did wrong, I
> would highly appreciate it.
>
> Thanks in advance: P=E9ter Juh=E1sz

Problem solved.

```

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