[TI-M] Re: complex matrixs etc. and also differential equations!!!


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[TI-M] Re: complex matrixs etc. and also differential equations!!!



Factor...factors...things.  Like the following expression:

factor(x^2-x-6)
    (x-3)(x+2)

Basically, it tries to get all parts of the expression to 
be multiplied together.

Sometimes the TI89 doesn't factor everything completely. 
 Why?  I don't know.  But, yeah, Jeff is correct.

So if you end up with an equation that doesn't look simple 
enough, try running this command: factor(expand(expr))

Like this:

(x^2-4)/(x^3-2x^2+4x-8) -> expr

Factoring this expression would yield this:

(x+2)(x-2)/((x^2+4)(x-2)), which the TI would 
automatically simplify down to: (x+2)/(x^2+4)

Seems simple enough, but the calculator does make mistakes 
from time to time.  (gasps of shock)  Yes, really.  That's 
what you get for trying to make an intelligent response 
system.

On Sat, 5 Apr 2003 12:19:29 +0200
  Pawel Zubkiewicz <krwawnik@box43.pl> wrote:
>Hi!
>
>jeff> expand will do all sorts of things, including 
>making partial fractions.  also, if you're ever
>jeff> getting answers that don't look simplified or 
>something weird like that, try messing around by
>jeff> expanding them and factoring them or vice versa. 
> sometimes it makes it collapse it more.  very
>jeff> strange.  
>
>so far i haven't used factor(), i (sad but true) dont 
>know what does
>it do. i've got my TI for 2 weeks only... so i have much 
>to learn
>
>
>jeff> now, differential equations.  does anyone know how 
>to make the 89 solve differential equations
>jeff> with greater than second derivative?  y''', etc. 
> it will take y' and y'', but gives argument
>jeff> error if you type y'''.  is there another format, 
>or does it just not support it at all?
>
>try Differantial equation solvers - DiffEq
>http://www.paxm.org/symbulator/download/diffeq.zip
>
>i'm sure you will be satisfied ;-)
>
>Zupa
>
>

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