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Homework Help: The domain of a function in interval notation

  1. Mar 15, 2012 #1
    1. what is the domain of the function k(y)=1/(2y+1)? Express your answer in interval notation


    2.



    3. I find that 0.5 is a possibility in this function, but since i have not done functions at school, i do not really know much more of this question.
     
  2. jcsd
  3. Mar 15, 2012 #2
    There are generally only two restrictions you have to look for when determining domain. If there is a fraction, the denominator cannot equal 0, and if there is an even numbered radical, the inside cannot be negative.
     
  4. Mar 15, 2012 #3

    HallsofIvy

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    "0.5 is a possibility" for what? It certainly is not the domain because it is not a interval. Are you claiming that 0.5 is in the domain?
     
  5. Mar 19, 2012 #4
    So what really is meant by the domain? Is it asking for all possible values of y?
     
  6. Mar 19, 2012 #5
    I mean that 0.5 could be y
     
  7. Mar 19, 2012 #6

    SammyS

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    All possible values for x .
     
  8. Mar 19, 2012 #7

    HallsofIvy

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    Good question! You can't solve a problem about the "domain" if you don't know what that word means. Did you consider looking the word up in your textbook?

    The "domain" of a function, f(x), is the set of all allowable values lf x. The set of all possible values of the function, y if we have y= f(x), is the "range" of the function.
     
  9. Mar 19, 2012 #8
    Nightshade,

    the domain of f(x)=[itex]\frac{2}{x-1}[/itex] for example is all real numbers except 1, because when x is 1 the denominator goes to 0, and the equation becomes undefined.

    This can be notated as D: x≠1 or D:(-∞,1)[itex]\cup[/itex](1,∞)
     
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