MathGroup Archive 1999

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Simplify: Which Sign

  • To: mathgroup at smc.vnet.net
  • Subject: [mg16831] Simplify: Which Sign
  • From: Remi Ricard <ricard at gmc.ulaval.ca>
  • Date: Tue, 30 Mar 1999 02:35:27 -0500
  • Sender: owner-wri-mathgroup at wolfram.com

I,

How can you know which sign the Fonction Simplify will give you 

My equation is 
eq1 = 4 C1^4 - 8 C1^2 lm1^2 + 4 lm1^4;

Using eq1 = Simplify[eq1];
I get eq1 = 4 (-C1^2 + lm1^2)^2;

which could have been eq1 = 4 (C1^2 - lm1^2)^2;

Since eq1 will be the input of a square root, I want to be able to 
decide which of the + or - solution I will use.
C1 = lm1 Cos[theta_1];
lm1 > 0;

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