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Math Help - Interval notation placement

  1. #1
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    Interval notation placement

    How do i know how the interval notiation set will be? I have attached a graph for an example =)

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    (5,-3] or is it [-3,5) plus i am confused with the brackets [ ( )]
    Attached Thumbnails Attached Thumbnails Interval notation placement-notation.png  
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  2. #2
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    Re: Interval notation placement

    Usually you would write this as {x: -3 < x <= 5} and then then interval notation would be (-3, 5].
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    Re: Interval notation placement

    It's (-3, 5]. The smaller value (taking the sign into account) must be on the left. The parentheses ( and ) correspond to strict inequalities < and >, while square brackets [ and ] correspond to non-strict inequalities \le and \ge.
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    Re: Interval notation placement

    \begin{gathered}(3,5)\; \equiv \,\left\{ {x:3 < x < 5} \right\} \hfill \\  (3,5]\; \equiv \,\left\{ {x:3 < x \leqslant 5} \right\} \hfill \\  [3,5)\; \equiv \,\left\{ {x:3 \leqslant x < 5} \right\} \hfill \\  [3,5]\; \equiv \,\left\{ {x:3 \leqslant x \leqslant 5} \right\} \hfill \\ \end{gathered}
    Last edited by Plato; September 12th 2011 at 03:12 AM.
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    Re: Interval notation placement

    Quote Originally Posted by Plato View Post
    \begin{gathered}(3,5)\; \equiv \,\left\{ {x:0 < x < 5} \right\} \hfill \\  (3,5]\; \equiv \,\left\{ {x:0 < x \leqslant 5} \right\} \hfill \\  [3,5)\; \equiv \,\left\{ {x:0 \leqslant x < 5} \right\} \hfill \\  [3,5]\; \equiv \,\left\{ {x:0 \leqslant x \leqslant 5} \right\} \hfill \\ \end{gathered}
    Ouch! Plato, what have you been smoking?
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    Re: Interval notation placement

    Quote Originally Posted by HallsofIvy View Post
    Ouch! Plato, what have you been smoking?
    Thanks, corrected!
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    Re: Interval notation placement

    Quote Originally Posted by HallsofIvy View Post
    Ouch! Plato, what have you been smoking?
    And where can I get some?
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    Re: Interval notation placement

    so if something has the infinite symbol '-' <------ similar to that than that symbol is moved to the right?
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    Re: Interval notation placement

    Quote Originally Posted by cytotoxictcell View Post
    so if something has the infinite symbol '-' <------ similar to that than that symbol is moved to the right?
    What on Earth are YOU smoking, and where can I get some? That's a "minus" or "negative"...

    This is infinite... \displaystyle \infty
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    Re: Interval notation placement

    Quote Originally Posted by Prove It View Post
    What on Earth are YOU smoking, and where can I get some? That's a "minus" or "negative"...

    This is infinite... \displaystyle \infty
    lol i am not smoking anything =). I just dont know how to make the infinite symbol. How did you do it so that it appears on the forum like you did?
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  11. #11
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    Re: Interval notation placement

    Quote Originally Posted by cytotoxictcell View Post
    lol i am not smoking anything =). I just dont know how to make the infinite symbol. How did you do it so that it appears on the forum like you did?
    Use LaTeX tags.
    [TEX]\infty[/TEX] gives \infty

    [TEX](-\infty,0][/TEX] gives (-\infty,0]

    [TEX](0,\infty)[/TEX] gives (0,\infty)
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