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Homework Help: Cubic Function Factoring

  1. Feb 4, 2009 #1
    1. The problem statement, all variables and given/known data
    factor -x^3 + 27


    2. Relevant equations



    3. The attempt at a solution

    Nothing, I have no idea how to factor it.
     
  2. jcsd
  3. Feb 4, 2009 #2

    Mark44

    Staff: Mentor

    Here are a couple of formulas for you:
    a3 + b3 = (a + b)(a2 - ab + b2)
    a3 - b3 = (a - b)(a2 + ab + b2)
     
  4. Feb 4, 2009 #3
    I tried those. My main problem is the -x^3.
     
  5. Feb 4, 2009 #4

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    You've got 3^3-x^3. That fits the second formula Mark44 gave you.
     
  6. Aug 15, 2009 #5
    2 seconds on physics forum and I found what i'm after. Thanks very much.
     
  7. Aug 15, 2009 #6

    HallsofIvy

    User Avatar
    Science Advisor

    Sorry we took so long!
     
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