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Math Help - () {} [] what do they mean again?

  1. #1
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    () {} [] what do they mean again?

    () this means it includes the #
    [] is it the same as {} this? and means it dose not include the # when writing in interval notation

    infinity always gets a parentheses correct?

    domain look left to right?
    range up down?
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by rj2001 View Post
    () this means it includes the #
    [] is it the same as {} this? and means it dose not include the # when writing in interval notation
    no, ( or ) means it does NOT include the number: x \in (0,1) \implies 0 < x < 1

    [ or ] means it the number is included: x\in (0, 1] \implies 0 < x \le 1

    {} as i usually see it deals with specific elements.

    example, we might write (- \infty,2) \cup (2, \infty) as \mathbb{R}\backslash \{ 2 \} \mbox{ or } (- \infty, \infty) - \{ 2 \} or something like that

    infinity always gets a parentheses correct?
    yes, always ( - \infty or \infty)

    domain look left to right?
    range up down?
    ...um, yeah. in a sense...
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