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MathGroup Archive 2000

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Re: transposing an equation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg26252] Re: [mg26234] transposing an equation
  • From: Maarten.vanderBurgt at icos.be
  • Date: Sun, 10 Dec 2000 00:19:29 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Christopher,

try
In[5]:= Solve[y == a x + b x^2 + c, x]
Out[5]= {{x -> (-a + Sqrt[a^2 - 4*b*c + 4*b*y])/(2*b)},
  {x -> -((a + Sqrt[a^2 - 4*b*c + 4*b*y])/(2*b))}}

And you will see there is no general way to re-write y = a x^2 + b x + c as
x = Ay^2 + By + C. Except for some special cases there will be a Sqrt[y] in
the solution.

Maarten van der Burgt
Leuven, Belgium





"Christopher Deacon" <cdeacon at physics.mun.ca> on 06-12-2000 08:16:20 AM


Subject: [mg26252]  [mg26234] transposing an equation




Suppose y=a x^2+b x +c.

How can I get Mathematica to solve for x (i.e., x=Ay^2+By+C) and give me
the
values for the constants A,B,C?

Chris

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