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Math Help - Functions

  1. #1
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    Thumbs down Functions

    is it always not a function when you have a negative variable?
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  2. #2
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    Quote Originally Posted by Russian View Post
    is it always not a function when you have a negative variable?
    y = -5x -1 is a function

    y = -x is a function

    y = - x^3-2x^2-x+4 is a function. Please specify clearly your question.
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  3. #3
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    Perhaps you are thinking of \sqrt{x} or log(x) which are not defined for negative values of x. But those are properties of those particular functions, not functions in general.

    Certainly simple functions, like x^2 or 3x- 2 are defined for all values of the variables, negative as well as positive.
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  4. #4
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    Smile

    Quote Originally Posted by HallsofIvy View Post
    Perhaps you are thinking of \sqrt{x} or log(x) which are not defined for negative values of x. But those are properties of those particular functions, not functions in general.

    Certainly simple functions, like x^2 or 3x- 2 are defined for all values of the variables, negative as well as positive.
    yes that is what i was thinking.
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