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Re: Solving multiple equations

  • To: mathgroup at
  • Subject: [mg125536] Re: Solving multiple equations
  • From: Bill Rowe <readnews at>
  • Date: Sun, 18 Mar 2012 02:40:45 -0500 (EST)
  • Delivered-to:

On 3/17/12 at 2:52 AM, tmatsoukas at (Themis Matsoukas) wrote:

>I have two set of equations, one in the form,

>eq1 = ({0.15, 0.85, X1} == {X3, X2 + X4, X5})

>and the other in the form

>eq2={1. X1 == 9/5, X4/(X3 + X4 + X5)==1/3}

>Solve understands both Solve[eq1] and Solve[eq2] but if I want to
>solve the two sets simultaneously, what is the best way to combine
>eq1 and eq2 into a single list of equations, either of the form of
>eq1 or of eq2, that Solve can understand?

In[24]:= NSolve[Join[Thread@eq1, eq2], {X1, X2, X3, X4, X5}]

Out[24]= {{X1->1.8,X2->-0.125,X3->0.15,X4->0.975,X5->1.8}}

I've used NSolve since the coefficients in the first set of
equations are machine precision values.

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