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Math Help - is this a function

  1. #1
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    is this a function

    Let f be the set of all ordered pairs (x,y) such that x and y belong to R and y = x2. Is this a function?
    The same question, for f be the set of all ordered pairs (x,y) such that x and y belong to R and x=y2. Is this a Function?



    I think for the first one y=x2 it is a function because there is a unique y value for every x value that is given.

    For the second one, I think that x=y2 is not a function because there is not a unique y value for every x. Because if x=2 then y can = -2 and 2.

    Is this right?

    Thanks for the help!
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  2. #2
    Super Member 11rdc11's Avatar
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    Your correct. Remember you can graph these and use the vertical line test to see if it is a function.
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  3. #3
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    thank you!!
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    not to nitpick, but if x = 2 then y can be \sqrt{2} or - \sqrt{2}

    but you have the concept right, so that's good. take note of 11rdc11's method as well. it comes in handy
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