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MathGroup Archive 1995

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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


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