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Inverse function warnings

  • To: mathgroup at smc.vnet.net
  • Subject: [mg99164] Inverse function warnings
  • From: davef <davidfrick2003 at yahoo.com>
  • Date: Wed, 29 Apr 2009 03:48:44 -0400 (EDT)

When I execute this in Mathematica 7:

Solve[3^(2 x) - 12 (3^x) + 27 == 0, x]

I get this:

Solve::ifun: Inverse functions are being used by Solve, so some solutions may not be found; use Reduce for complete solution information. >> 

{{x->1},{x->2}}


1 amd 2 are proper solutions but is it possible to avoid the warning?

If I use Reduce:

Reduce[3^(2 x) - 12 (3^x) + 27 == 0, x]

I get a set of 1 and 2 added to some imaginary number terms that I don't quite understand.

I guess my question is: why would the use of inverse functions be so unreliable a solution as to necessitate a warning?  And in the interest of clean output, can the warning be supressed other than by deleteing the cell?  

Thanks


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