Chapter 0: Problem 5
Express each interval in set-builder notation and graph the interval on a number line. $$[-3,1]$$
Short Answer
Expert verified
The set-builder notation for the interval \([-3,1]\) is \({x|-3\leq x\leq 1}\)
Step by step solution
01
Identify the Interval
The given interval is \([-3,1]\). This means x is in the interval from -3 to 1 inclusive. This is a closed interval, which means it includes the endpoints.
02
Convert to Set-builder notation
The set-builder notation of a given interval is defined as \({x|-3\leq x\leq 1}\). This can be read as 'the set of all x such that x is greater than or equal to -3 and less than or equal to 1'. This implies all the real numbers between -3 and 1 inclusive.
03
Graph the Interval
To represent this on a number line, mark -3 and 1 and darken the line between them to indicate the interval. As the interval is closed at both ends (-3 and 1 are included in the set), small darkened circles are drawn at these points.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Set-builder notation
Set-builder notation is a concise way of representing a set by specifying a property that its members must satisfy. It is widely used in mathematics to define intervals of numbers. For instance, the set-builder notation for the interval
- Represents a set by describing the properties of its elements.
- Uses a variable, such as \(x\), and conditions to define the set.
- An example is \(\{x \mid -3 \leq x \leq 1\}\), which reads as "the set of all x such that \(-3\) is less than or equal to \(x\) and \(x\) is less than or equal to \(1\)."
Closed interval
A closed interval is an interval that includes its endpoints. In mathematical notation, the closed interval from \(a\) to \(b\) is represented as
- Indicated by square brackets: \([a, b]\).
- Includes all numbers \(x\) such that \(a \leq x \leq b\).
- The endpoints are part of the set, unlike open intervals which use parentheses (e.g., \((a, b)\)) to exclude endpoints.
Number line
Number lines provide a straightforward way to visualize and understand intervals. It's a horizontal line with numbers placed at equal intervals, typically centering on zero. To graph a closed interval on a number line:
- Identify the endpoints of the interval. For \([-3, 1]\), these are \(-3\) and \(1\).
- Darken or draw a line connecting these two points to show the range of the interval.
- Fill in the circles at the endpoints to indicate they are included in the interval.
Inequalities
Inequalities are mathematical expressions involving a relational operator, explaining how one number compares to another. There are various types of inequalities that determine the inclusion or exclusion of numbers. The key aspects include:
- Use symbols such as \(\leq\) (less than or equal to) and \(\geq\) (greater than or equal to).
- For the closed interval \([-3, 1]\), the inequality \(-3 \leq x \leq 1\) indicates \(x\) can be any number between \(-3\) and \(1\), inclusive.
- Inequalities help us describe an interval's boundaries mathematically.