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Definition of Absolute Value of a Function

  1. Feb 9, 2007 #1
    1. The problem statement, all variables and given/known data
    Question straight off the book "In this lesson, you have explored the absolute value of a function. How is it defined?"

    2. Relevant equations
    In this lesson, I did questions like xE[0,9] and was told to write each intervals in absolute value notation.

    3. The attempt at a solution
    I have no idea on where to start. Please help.
  2. jcsd
  3. Feb 9, 2007 #2


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    Staff Emeritus
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    Start by showing us what definition of Absolute value you are working with?
  4. Feb 9, 2007 #3


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    Staff: Mentor

    The absolute value just means the value as a positive quantity. If you take the absolute value of a negative quantity, you get the corresponding positive quantity. Like, |-5| = 5.

    I don't understand the notation xE[0,9], however, and writing an "interval in absolute value notation" doesn't make much sense to me. An interval is traditionally a subset of the independent axis, while the function over that interval is plotted on the dependent axis. Can you clarify?
  5. Feb 9, 2007 #4
    xE[0,9] is an example of interval notation, read "x is an element of the closed interval from 0 to 9". It sounds like your book wants the piecewise definition. Ill give you a hint, the 2 cases are x>0 and x<0
  6. Feb 9, 2007 #5


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    Staff: Mentor

    Oh, I get it now. Thanks. It was the use of a standard letter "E" that fooled me. I'd use the \in function in LaTex:

    [tex]x \in [0,9][/tex]
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