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Re: Simple question: is it possible to take a derivative and solve for x ?

From Bill Rowe <readnews@sbcglobal.net>
Newsgroups comp.soft-sys.math.mathematica
Subject Re: Simple question: is it possible to take a derivative and solve for x ?
Date 2011-05-30 10:33 +0000
Organization Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID <irvrq1$8h0$1@smc.vnet.net> (permalink)

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On 5/29/11 at 7:36 AM, t27026t@yahoo.com.br (Alonso) wrote:

>I am a beginner, and would like to know if it is possible to solve
>for x the first derivative of a long equation in Mathematica. Bear
>with me, my background is in Biomedical Sciences.

>I am typing the following command:

>Solve[D[((x*l1 + (1 - x)*l2)/((x^2*v1 + (1 - x)^2*v2 +  2*x*(1 -
>x)*c)^0.5))+((x*L1 + (1 - x)*L2)/((x^2*V1 + (1 - x)^2*V2 +  2*x*(1 -
>x)*C)^0.5)), x]==0,x]

>But Mathematica 8 simply stops, and no output is given.

A portion of the difficulty is likely to be the term

  2*x*(1 - x)*C)^0.5)

  C cannot be used as a variable since it has built-in meaning.
Try changing this to a lower case c and see if that helps. It is
a good idea to avoid using single upper case letters as
variables so as to avoid conflicts with built-in symbols.

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Re: Simple question: is it possible to take a derivative and solve for x ? Bill Rowe <readnews@sbcglobal.net> - 2011-05-30 10:33 +0000

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