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Difference between different types of brackets used

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winnerhere Really wants to Beat The GMAT! Default Avatar
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Difference between different types of brackets used Post Thu Sep 03, 2009 5:19 am
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  • Lap #[LAPCOUNT] ([LAPTIME])
    Whats the difference between square brackets,parenthesis and flower brackets in mathematics

    [0,5]

    (0,5)

    [0,5)

    are all different ranges.

    Thanks in advance Smile

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    DanaJ Site Admin
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    Post Thu Sep 03, 2009 5:40 am
    If you have a square bracket, the interval also contains the "head" of the interval. If it's just a round bracket, then that head is not included.
    In your examples:

    [0,5] means 0 <= x <=5

    (0,5) means 0 < x < 5

    [0,5) means 0 <= x < 5

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    winnerhere Really wants to Beat The GMAT! Default Avatar
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    Post Thu Sep 03, 2009 7:20 am
    Thanks danaj Smile

    what abt {}

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    Ian Stewart GMAT Instructor
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    Post Thu Sep 03, 2009 2:21 pm
    Dana's explanation is perfect, but I've never seen a real GMAT question which uses that notation for an interval (ranges of values are always expressed using inequalities, a number line, or words), so you likely don't need to know it. In algebra, square brackets [] and parentheses () have the same meaning (in algebra texts, you'll sometimes see square brackets used as outer brackets when there are brackets within brackets), though I don't think I've ever seen that on the GMAT either - I'm pretty sure the GMAT uses standard parentheses exclusively in algebraic expressions. Set braces {} will only be used in a question about sets, so if you see something like {6}, that's the one element set containing the number 6.

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    Post Thu Sep 03, 2009 10:11 pm
    On top of what Ian said, we also have this notation in Romania:

    {2.34} = 0.34
    {3} = 0

    We call this the "fractional part" of a number. However, seeing this on the GMAT is impossible, since I understand it is a pretty specific notation.

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