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MathGroup Archive 2000

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Re: Simple equation checking..

  • To: mathgroup at smc.vnet.net
  • Subject: [mg25665] Re: Simple equation checking..
  • From: "Bill Bertram" <wkb at ansto.gov.au>
  • Date: Wed, 18 Oct 2000 02:52:34 -0400 (EDT)
  • Organization: Australian Nuclear Science and Technology Organisation
  • References: <8seb1e$6tb@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Ian Fan <ian at v-wave.com> wrote in message news:8seb1e$6tb at smc.vnet.net...
>
> Hi again, thanks for all the help with my last question but now I am stuck
> with another problem if anyone would be so kind enough to help.
>
> I am looking for a way to check equations, for example, the derivative of
> ((x^3 - 4x + 3)/x^(4/3) is (5x^(10/3) - 8x^(7/3) - 12x^(1/3))/(3x^(8/3))
> when calculated via hand but is (3x^2 - 4)/x^(4/3) - 4(x^3 - 4x +
> 3)/(3x^(7/3)) when put through mathematica.

Simply use the A == B statement to check for true or false! For your example
Mathematica will only return a true/false result if the statement is
actually true for all values of x. If the statement is not true in general
it may well be true for certain values of x so Mathematica does cannot give
the result "false".



> What I would like to do is if
> there is any way to equate the two and see if the statement is true
because
> obviously it can look like two completely different answers (to a student)
> when they are in fact the same.

...but the two expressions you have given  above, are not the same! Try
evaluating them with x=1.

 > Another example would be, is there any way to check if E^(:ii:Pi) = -1
was
> true (at least according to the Euler-Moivre equation), using Mathematica?

Yes,
               E^(:ii:Pi) ==  -1

gives the result   "true"



Cheers,

     Bill




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