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Math Help - What's wrong with my answer? (Finding equations)

  1. #1
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    What's wrong with my answer? (Finding equations)

    Given f(x) = 3 - x - x^2, find equation of -f(x)

    The teacher didn't like my answer, what's wrong with the way I wrote this?

    f(x) = 3 - x - x^2
    f(x) = -(3 - x - x^2)
    f(x) =  -3 - (-x) - (-x^2)
    f(x) = -3 + x - x^2

    I don't know what I did wrong...

    edit: I meant -f(x)
    Last edited by swtdelicaterose; February 17th 2010 at 07:25 PM.
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  2. #2
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    f(x) = 3 - x - x^2

     f(-x) = 3 - (-x) - (-x)^2 = 3+x-x^2
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  3. #3
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    Sorry, meant -f(x).

    So what's wrong with the way I wrote it?
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  4. #4
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     <br />
- f(x) = -(3 - x - x^2)<br />
    Last edited by pickslides; February 17th 2010 at 07:54 PM.
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  5. #5
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    your last line
    should be -3 + x + x^2
    the last + you have as a -
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