Re: Simplify expression

*To*: mathgroup at smc.vnet.net*Subject*: [mg57830] Re: Simplify expression*From*: dh <dh at metrohm.ch>*Date*: Thu, 9 Jun 2005 05:55:31 -0400 (EDT)*References*: <d8697g$c9t$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hi Muktar, what you want to do involves assumptions that you must specify. E.g.: Assuming[x1^2 > x2^2, Sqrt[(x1^2 - x2^2)^2] // Simplify] will do what you want. sincerely, Daniel Mukhtar Bekkali wrote: > I need to solve system of equations f1[x1,x2]=0,f2[x1,x2]==0, however, > some elements of these equation have the form Sqrt[(x1^2-x2^2)^2]. It > takes really long time to solve. If, however, I manually simplify > those elements, for example, Sqrt[(x1^2-x2^2)^2]=x1^2-x2^2 then solve > is fast. Therefore, the question is how I can force mathematica > simplify expressions of this sort (another elements are fractions that > depend on x1 and x2 in Mathematica's mind but in reality they cancel > out and fraction becomes a number). I do not want to use FindRoot since > I want to see all solutions. Thanks, Mukhtar Bekkali >