Re: simultaneous equations
- To: mathgroup at smc.vnet.net
- Subject: [mg2236] Re: simultaneous equations
- From: danl (Daniel Lichtblau)
- Date: Wed, 18 Oct 1995 01:53:35 -0400
- Organization: Wolfram Research, Inc.
In article <DGIy5I.I8x at wri.com> heath andersen <ha20 at uow.edu.au> writes:
>
> i am having trouble solving this set of simultaneous equations.
> <deleted>
> also, [q7880]^2 = [q78 + q80]^2
>
> Here is exactly what i typed in and what Mma gave me back.
>
>
--------------------------------------------------------------------------
--
> --------
> p78 = p80 = p81 = 101300
> 101300
>
> p788081 = 100100.6
> 100100.6
>
> r78 = r80 = 220
> 220
>
> r81 = 219.5
> 219.5
>
> r7880 = 54.86
> 54.86
>
> Solve[{ p78 - p7880 == q78^2 * r78,
> p80 - p7880 == q80^2 * r80,
> p7880 - p788081 == r7880[q78 +q80]^2,
> p81 - p788081 == q81^2 * r81},
> {q78, q80, p7880, q81}]
> Solve::tdep:
> The equations appear to involve
> transcendental functions of the
> variables in an essentially
> non-algebraic way.
><deleted>
> thanks
>
> h.andersen
> university of wollongong
> nsw australia
>
Use parentheses instead of brackets to parenthesize your subexpressions.
Solve[{ p78 - p7880 == q78^2 * r78,
p80 - p7880 == q80^2 * r80,
p7880 - p788081 == r7880*(q78 +q80)^2,
p81 - p788081 == q81^2 * r81},
{q78, q80, p7880, q81}]
will work just fine.
Daniel Lichtblau
Wolfram Research
danl at wri.com