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Re: HELP! algebraic math problem

  • Subject: [mg2947] Re: HELP! algebraic math problem
  • From: wfigueroa at mosquito.com (wilson figueroa)
  • Date: 14 Jan 1996 05:20:21 -0600
  • Approved: usenet@wri.com
  • Distribution: local
  • Newsgroups: wri.mathgroup
  • Organization: Mosquito Net, Inc.
  • Sender: mj at wri.com

David,

Since you have an equation which involves a transcendental
function, it is almost always impossible to find a closed
form solution involving x only.

At this point one needs to resort to numerical techniques.

Here you can use FindRoot[f(x) == 0, {x,x0}].  For example,

FindRoot[10*Log[x] + 2*x - 3 == 0,{x,4},
         WorkingPrecision -> 30]

would yield,

x = 1.0862...(to thirty places)

Note that I would recommend plotting the function over a range
of x.  Obviously here, x must be > 0, and plotting will help
you to see the zeros of the function.  Have fun

Wilson.



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