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3.2: [a, b)

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    This section will study intervals in the form \([a,b)\). The interval begins with a left bracket and ends with a right parentheses. Starting the interval with a brackets means the right endpoint is included in the set and ending with the use of a parentheses means the left endpoint in not included.

    Example 3.2.1

    \([2,5)\)

    Solution
    clipboard_e00011d80a3add869d79e38285855cdb0.pngFigure 3.2.1

    In the example above, the interval starts with a left bracket and ends with a parentheses. Hence,the interval includes the number 2 and does not include the number 5. By observing the corresponding number a closed bullet \(\bullet\) is used to demonstrate that the number 2 is included in the interval, on the other hand an open bullet \(\circ\) is on the number 5 to demonstrate that 5 in not in the interval. Some of the numbers in the set include 2, 2.5, 3.4, 4 and 4.99. Again, the number 5 is not in this set.

    Example 3.2.2

    \([-4,10)\)

    Solution
    clipboard_e4a4db8d37751faeb6b0ef1e69ab11a08.png
    Figure 3.2.2

    Similar to example 1, the endpoint on the left which corresponds to the number -4 is included in the interval, while the endpoint on the right is not included in the interval. Some numbers on the interval above are -4, -2, 0, 3.5, 8.5 and 9.9.

    Exercise 3.2.1

    Draw a number line for the following intervals and list at least three numbers inside the set.

    1. \([-3,1)\)
    2. \([-12,-2)\)
    3. \([-233,-223)\)
    4. \([3.5,5)\)
    5. \([0,1)\)
    6. \([-1.4,2.8)\)

    This page titled 3.2: [a, b) is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by Victoria Dominguez, Cristian Martinez, & Sanaa Saykali (ASCCC Open Educational Resources Initiative) .

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