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Math Help - Interval Notation

  1. #1
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    Interval Notation

    Are the following interval notations correct?

    1. x is in R, x not equal 1 ----> R\{1}

    2. x<1 or x>3 ----> R\[1,3]

    3. x=1, x>3 ----> {1}U(3, infinity)

    Thanks!!!
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  2. #2
    MHF Contributor Amer's Avatar
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    Quote Originally Posted by acc100jt View Post
    Are the following interval notations correct?

    1. x is in R, x not equal 1 ----> R\{1}

    2. x<1 or x>3 ----> R\[1,3]

    3. x=1, x>3 ----> {1}U(3, infinity)

    Thanks!!!
    you are correct
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  3. #3
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    Quote Originally Posted by acc100jt View Post
    Are the following interval notations correct?

    1. x is in R, x not equal 1 ----> R\{1}

    2. x<1 or x>3 ----> R\[1,3]

    3. x=1, x>3 ----> {1}U(3, infinity)

    Thanks!!!
    I disagree on (1) and (2). Those are not "interval notation". The first should be written as (-\infty, 1)\cup (1, \infty) and the second as (-\infty, 1)\cup (3, \infty)
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  4. #4
    Newbie Bill Zimmerly's Avatar
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    Wink

    Quote Originally Posted by HallsofIvy View Post
    I disagree on (1) and (2). Those are not "interval notation". The first should be written as (-\infty, 1)\cup (1, \infty) and the second as (-\infty, 1)\cup (3, \infty)
    I disagree too. Download this video:



    Where Dr. Delaware discusses interval notation somewhere in the middle of the lesson.
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  5. #5
    MHF Contributor Amer's Avatar
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    I did not pay attention to the thread subject it is about intervals, sorry
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  6. #6
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    ok. Thanks a lot.

    Anyway, am I allowed to remove an interval from real numbers, like R\[1,3],
    is this notation ok?

    and can i union a set and an interval, like \{1\}\cup (3, \infty)?
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