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Homework Help: Polynomial functions, descartes rule

  1. Dec 3, 2007 #1
    [SOLVED] polynomial functions, descartes rule

    1. f (–x) = (–x)^5 – (–x)^4 + 3(–x)^3 + 9(–x)^2 – (–x) + 5




    2. Relevant equations



    3. = –x^5 – x^4 – 3x^3 + 9x^2 + x + 5

    but isn't a negative x a negative suppose to = positive?

    so shouldnt – (–x)^4 = x^4 instead of – (–x)^4 = -x^4 ?
     
    Last edited: Dec 3, 2007
  2. jcsd
  3. Dec 3, 2007 #2

    No, because you must follow the order of operations:

    [tex]-(-x)^4 = -[ (-x)^4] = -[x^4] = -x^4[/tex]

    Parentheses come first, then exponentiation, then negation (in this problem).
     
  4. Dec 3, 2007 #3
    ok...hehhe...I'ma dumbass.....

    can't believe I missed that

    thnkx. cheers
     
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