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Homework Help: Y as a function of x

  1. Oct 12, 2006 #1
    Hmm I'm not sure if this is correct:

    Problem: Decide whether the equation represents y as a function of x:


    Ok, so do square roots always have the plus/minus sign automatically? Radicals are the equivalent of sleep parabolas right?? Do I add the bottom half also??

    My answer was No because it is a radical/sleeping parabola.
  2. jcsd
  3. Oct 12, 2006 #2


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    Science Advisor

    No, [itex]\sqrt{x}[/itex] is defined as the positive number whose square is equal to x. Square root, like any real valued function, is single valued.

    "Sleeping" parabola? You mean a parabola with its axis horizontal?
    Unfortunately, you are wrong. [itex]\sqrt{x+3}[/itex] is a function. It's graph is the top half of the horizontal parabola.
  4. Oct 12, 2006 #3
    it is a function because it passes the vertical line test. usually the square root means the principal square root.
  5. Oct 12, 2006 #4
    ok thanks.
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