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  • To: mathgroup at
  • Subject: Solve
  • From: vdaele at (Marc Van Daele)
  • Date: Tue, 31 Aug 93 09:52:23 +0200


I have two quite simple equations which Mma is not able to solve.
Any ideas why?

Solve[{(mu*S0*X0*(1 - y))/y == a0,
       (mu^2*S0*X0^2*(-1 + y))/y^2 == a1}, {mu, S0}]

takes indefinetely (at least several hours)

So I need to help Mma like this: 
- first solve S0 from first equation, next replace that solution in second
  equation and solve mu from that equation

sol1s0  = Flatten[Simplify[
		Solve[(mu*S0*X0*(1 - y))/y == a0, S0]]] 
sol1mu  = Flatten[Simplify[
		Solve[(mu^2*S0*X0^2*(-1 + y))/y^2 == a1 /. sol1s0, mu]]]
sol1s0  = Flatten[Simplify[sol1s0 /. sol1mu]]

Which results in
         a1 y
{mu -> -(-----)}
         a0 X0

{S0 -> ----------}
       -a1 + a1 y

Why is this set of equation so difficult for Mma.
And is there an easier way to solve these equations than holding Mma's hands 
like this.  (I also have a similar problem with six variables)

Thanks for any help,

Marc Van Daele
vdaele at

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