Re: Simple equation checking..

*To*: mathgroup at smc.vnet.net*Subject*: [mg25654] Re: Simple equation checking..*From*: Yossi Lonke <jrl16 at po.cwru.edu>*Date*: Wed, 18 Oct 2000 02:52:26 -0400 (EDT)*Organization*: Dept. Mathematics, CWRU*References*: <8seb1e$6tb@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Hello, The derivative you calculated by hand is not correct, so not only don't the results look the same, they are in fact not the same. In general, a robust way is to use Simplify[a-b] where a is your expression and b is Mathematica's expression. In most cases (algebraic functions for sure) the simplification would yield zero when the two expressions are the same. Yossi Lonke Ian Fan wrote: > 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). > > Thanks in advance, > Ian Fan -- ************************************************* Dr. Yossi Lonke Mathematics Department Case Western Reserve University 10900 Euclid Avenue Cleveland, Ohio 44106 216 368-5423 http://www.cwru.edu/artsci/math/lonke/home.html *************************************************