Monday, August 24, 2009

rational root thm. anyone?

okay, so i'm having trouble with this whole "rational root theorem" thing. I know that in the first step, you have to list all P: and Q: possibilities, +/- a,... but, is P your constant or your leading? And then you plug into your calculator all possibilities, +/-(a/b). From there I get confused. By plugging in all possibilities, until you get zero, that is, you find which +/-(a/b) combo. works. After that, I'm completely stranded in the middle of nowhere. If someone could pleasee help!
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8 comments:

  1. ArchimedesAugust 25, 2009 at 6:23 AM

    Look at your notes. It explains what p is. Once you find one that works you do the synthetic division with it. Follow the steps! :) I feel as though that should be a song like follow the yellow brick road.

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  2. TERRIOAugust 25, 2009 at 5:44 PM

    well in the notes it says P is all factors of the constant. And when you find the zero then you factor out the zero by using synthetic division. after that you do synthetic division again to find any more zeros. when you are done you should have 4 coordinates for your answer.

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  3. Weber121August 25, 2009 at 6:20 PM

    not necessarily terrio. it will only be 4 coordinates if the problem is a quartic eqn.

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  4. AnonymousAugust 26, 2009 at 6:58 AM

    well p is your constant and after you find your root from using the table, you use synthetic division twice and use simple algebra for the last part of the equation and you should come out with your answers

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  5. TERRIOAugust 26, 2009 at 4:30 PM

    haha yeah thats what i meant D.W.

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  6. GlitcherAugust 26, 2009 at 5:08 PM

    I see what you guys are saying on the rational root theorem and all but how does one go about grouping them after synthetic division like Mrs. Robinson showed us?

    E.G. p. 83 number 19
    x^4+2x3-6x-3
    p= +/-1,+/-3
    q= +/-1
    possibilities... plug into calculator... okay synthetic division

    -1/ 1 2 -2 -6 -3
    -1 -1 3 3
    -----------------
    1 1 -3 -3 0
    then she went on to group them as
    (x+1)(x^3+x^2-3x-3)
    where does the x+1 come from?
    ALSO
    -1/ 1 1 -3 -3
    -1 0 3
    ---------------
    1 0 -3 0
    (x+1)(x+1)(x^2-3)=0
    how in the world did you guys come up with this?!

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  7. GlitcherAugust 26, 2009 at 7:01 PM

    This comment has been removed by the author.

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  8. GlitcherAugust 26, 2009 at 7:09 PM

    and the above was a failed attempt at typing synthetic division correctly... >.<

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