       Solve

• To: mathgroup at yoda.physics.unc.edu
• Subject: Solve
• From: vdaele at ieper.lhs.be (Marc Van Daele)
• Date: Tue, 31 Aug 93 09:52:23 +0200

```Hi,

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

1)
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)
(NextStation)

2)
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

2
a0
{S0 -> ----------}
-a1 + a1 y

3)
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 lhs.be

```

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