RE: Simple equation checking..

• To: mathgroup at smc.vnet.net
• Subject: [mg25661] RE: [mg25625] Simple equation checking..
• From: "David Park" <djmp at earthlink.net>
• Date: Wed, 18 Oct 2000 02:52:31 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```Ian,

I believe that your hand differentiation is incorrect.

If you want to check if two expressions are equal

expression1 == expression2//Simplify  or
expression1 - expression2 == 0 //Simplify

will often work.

Mathematica gives:

E^(I*Pi) == -1
True

Check is really an advanced Mathematica programming command for handling
errors in complicated calculations and does not apply to simple checking of
equations.

David Park

> -----Original Message-----
> From: Ian Fan [mailto:ian at v-wave.com]
To: mathgroup 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. 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.
>
> 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?
>
> I tried using the "Check" command but I don't know what two
> arguments there
> are (I tried putting in lhs,rhs but I just got the former as an output).
>