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Math Help - Derivatives on TI-89 not working

  1. #1
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    Derivatives on TI-89 not working

    Hi,
    I've looked everywhere online and everything says to just to use d(f(x),x) to get a derivative and do integrals the same way. But I keep getting numbers.
    I put in d(x^2,x) and I get 0.000106 for example.
    I put in S(x^2,x) and I get 4.91563E-14.
    Shouldn't I be getting functions? Is there a setting you need before you can do derivatives and integrals?
    Thanks very much if you can help
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  2. #2
    Eater of Worlds
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    Chaneysville, PA
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    There is something stored in the variable x. As a matter of fact, I can tell you it is x=0.000053.
    You must clear the variable.

    Type in delvar(x) and then hit ENTER to clear x. The screen should then display "Done".

    If you want to clear them all, then do this:

    Hit F6 and then 'Clear a-z', then ENTER. It should then have a screen that says, "Clear 1-character variables a-z from current folder". Click on ENTER and you're all set. Then try your calc problems.
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  3. #3
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    Thanks so much!! That worked perfectly!
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