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Math Help - Define Function

  1. #1
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    Define Function

    Tell me, why is x = |y| NOT a function?

    Also, would y = |x| be a function? If so, why?
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  2. #2
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by sharkman View Post
    Tell me, why is x = |y| NOT a function?

    Also, would y = |x| be a function? If so, why?
    A function is where a value of x corresponds to exactly one value of y.

    With this equation it is clear that f(-4) = f(4) and so is not a function
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  3. #3
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    So...

    Quote Originally Posted by e^(i*pi) View Post
    A function is where a value of x corresponds to exactly one value of y.

    With this equation it is clear that f(-4) = f(4) and so is not a function
    So, x = |y| means that y varies in terms of values and thus making this equation NOT a function, right?

    Is that what makes it different from y = |x|?
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  4. #4
    Super Member Matt Westwood's Avatar
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    Because you can plug in any value of x and you can be guaranteed to get exactly one value of y out the other end. That's what defines a function: every value of x has exactly one value of y.
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  5. #5
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    ok...

    Quote Originally Posted by Matt Westwood View Post
    Because you can plug in any value of x and you can be guaranteed to get exactly one value of y out the other end. That's what defines a function: every value of x has exactly one value of y.
    Easily explained.
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