3.4: (a, b)

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Page ID: 45160

Victoria Dominguez, Cristian Martinez, & Sanaa Saykali
Citrus College via ASCCC Open Educational Resources Initiative

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In this section, both endpoints are not included in the interval.

Example 3.4.1

$(2,5)$

Solution

The interval above includes all numbers between 2 and 5, but because the interval has parentheses on both the left and the right sides of the interval, the end points are not included.

Example 3.4.2

$(-4,10)$

Solution

Similar to the explanation for the previous examples, the end points are not included in the interval. So the interval includes every number between -4 and 10, but not -4 and 10.

By now, students should have a strong idea of the numbers that are included and not included in the examples above. Students should also be able to analyze any given number line and write the appropriate interval notation for that number line. Try the following exercises to check for understanding.