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Roots of x^3 + 216

  1. Sep 18, 2004 #1

    Alkatran

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    I need to factorise x^3 + 216 to include (x+6):

    (x + 6) \ (x^3 + 216) (lim where x approaches -6)

    I broke it down to (x + 6i)(x^2 - 36i) ... but that's no good.
     
  2. jcsd
  3. Sep 18, 2004 #2

    arildno

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    Well, shouldn't polynomial division work fine?
     
  4. Sep 18, 2004 #3

    Pyrrhus

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    Remember

    [tex] X^3 + Y^3 = (X+Y)(X^2-XY+Y^2) [/tex]
     
  5. Sep 18, 2004 #4

    Pyrrhus

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    He has

    [tex] \frac{x+6}{x^3 + 216} [/tex]

    [tex] \frac{x+6}{x^3 + 6^3} [/tex]
     
  6. Sep 18, 2004 #5

    Alkatran

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    I got it fine before I even came back. I was trying to remember how to do long division and the cube rule that you guys posted. The start of the year, still getting restarted...
     
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