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Ok I'm a little confused with this: 16x-y^4=0

  1. Oct 7, 2006 #1
    Ok I'm a little confused with this:


    When you solve for (y) you get: y= plus/minus 4th root(16x) right?
    There for it isn't a function.

    What about y=sq.rt.(1-x)? Does it have the plus/minus automatically? Do you only put the plus/minus sign if you solve for y?

    I just don't get when you have to put the plus/minus in front of the sq.rt. Do you always have to put one there? or only if you solve for y, etc.?
  2. jcsd
  3. Oct 7, 2006 #2


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    Well, the even root of a number is DEFINED to be the positive number.
    That is, by definition, [itex]\sqrt{1-x}[/itex] is a positive number.

    When you solve for y, however, you must remember that not only do you have the positive, even root as a solution, but also the negative of that number.
  4. Oct 7, 2006 #3
    Oh ok. So if they give you an equation that has no plus/minus infront of it, then the equation is POSITIVE. However, if you solve for y and get a sq.rt. then you must put the plus/minus sign right? Thanks.
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