Chapter 2: Problem 52
Graph each compound inequality and describe the graph
using interval notation.
$$
-1
Short Answer
Expert verified
The graph is between \(-1\) (open circle) and \(4\) (closed circle); interval: \((-1, 4]\).
Step by step solution
01
Understand the inequality
The given compound inequality is \(-1 < x \leq 4\). This means that \(x\) is greater than \(-1\) and less than or equal to \(4\). We interpret this as all values between \(-1\) and \(4\), not including \(-1\) but including \(4\).
02
Set Up the Number Line
Draw a horizontal number line. Identify the points \(-1\) and \(4\) on the line. These are the critical values which define the boundaries for \(x\).
03
Plot the Graph
On the number line, draw an open circle at \(-1\) to indicate that \(-1\) is not included in the solution set. Draw a closed circle at \(4\) to indicate that \(4\) is included. Shade the region between \(-1\) and \(4\) to represent all \(x\) values in this range.
04
Write the Interval Notation
The interval notation for the compound inequality \(-1 < x \leq 4\) is written as \((-1, 4]\). Here, \((-1\) indicates that \(-1\) is not included and \(4]\) indicates that \(4\) is included.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Interval Notation
Interval notation is a way to express the set of solutions to an inequality in a concise manner. It provides a clear visual representation of which values are included or excluded in a range. In the context of the compound inequality \(-1 < x \leq 4\), interval notation simplifies the expression using parentheses and brackets.
Here’s how it works:
Here’s how it works:
- Parentheses, like \( ( \) or \( ) \), denote that a number is not included in the interval. For the inequality above, \(-1\) is not included, so it is written with a parenthesis: \((-1\).
- Brackets, like \( [ \) or \( ] \), indicate that a number is included in the interval. Since \(4\) is included in the set, use a bracket: \([4\).
Number Line
A number line is a straight, horizontal line that is used to represent numbers and intervals. This is a great visual tool in math to identify ranges and solutions of inequalities. Drawing a number line for the given inequality \(-1 < x \leq 4\) involves a few simple steps:
- Start by marking the critical points on the line. For this inequality, these are \(-1\) and \(4\), as they establish the boundaries of the solution set.
- Each point represents an important boundary of the inequality.
Open and Closed Circles
On a number line, circles are used to indicate whether a certain endpoint or boundary is included in an interval or not. For our inequality \(-1 < x \leq 4\), understanding these circles is key to correctly representing the solution:
- Open circles are drawn at endpoints that are not part of the solution set. In the interval \(-1 < x\), \(-1\) is not included—hence, we place an open circle at \(-1\).
- Closed circles represent endpoints that are included. For \(x \leq 4\), \(4\) is part of the solution, so you use a closed circle at \(4\).