Chapter 8: Problem 73
Solve each compound inequality, if possible. Graph the solution set (if one
exists) and write it using interval notation.
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-6
Short Answer
Expert verified
The solution is \(1 < x \leq 3\) or interval notation: \((1, 3]\).
Step by step solution
01
Set up Compound Inequality
The compound inequality is given as \(-6 < f(x) \leq 0\), where \(f(x) = 3x - 9\). We will set up two separate inequalities to solve for \(x\): \(-6 < 3x - 9\) and \(3x - 9 \leq 0\).
02
Solve the First Inequality
To solve \(-6 < 3x - 9\), add 9 to both sides to isolate the term with \(x\): \(-6 + 9 < 3x\), which simplifies to \(3 < 3x\). Next, divide both sides by 3: \(1 < x\) or \(x > 1\).
03
Solve the Second Inequality
For the inequality \(3x - 9 \leq 0\), add 9 to both sides: \(3x \leq 9\). Then, divide by 3 to solve for \(x\): \(x \leq 3\).
04
Combine the Inequalities
Combine the solutions from the separate inequalities: \(x > 1\) and \(x \leq 3\). This can be expressed as \(1 < x \leq 3\).
05
Graph the Solution Set
Graph the inequality on a number line. Open circle at 1 (because \(x\) is not equal to 1) and closed circle at 3 (because \(x\) can be equal to 3). Shade the region between these points to represent \(1 < x \leq 3\).
06
Write in Interval Notation
Express the solution set in interval notation. Since \(1 < x \leq 3\), the solution set is \((1, 3]\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Inequality Notation
Inequality notation is a mathematical way of expressing that one value is larger or smaller than another value. It uses symbols like "<" for "less than," ">" for "greater than," "≤" for "less than or equal to," and "≥" for "greater than or equal to."
In the exercise, the compound inequality is initially expressed as \(-6 < f(x) \leq 0\). This includes two parts:
This notation is particularly helpful for visualizing what values are included within a set of solutions that satisfy given conditions.
In the exercise, the compound inequality is initially expressed as \(-6 < f(x) \leq 0\). This includes two parts:
- \(-6 < f(x)\): This means that \(f(x)\) is greater than \(-6\).
- \(f(x) \leq 0\): This indicates that \(f(x)\) is less than or equal to \(0\).
This notation is particularly helpful for visualizing what values are included within a set of solutions that satisfy given conditions.
Number Line Graphing
Graphing solutions on a number line is an effective way to visually represent the range of solutions to an inequality.
For our solved inequality, \(1 < x \leq 3\), we need to show all \(x\)-values that fall strictly greater than 1 and up to and including 3.
To graph this:
For our solved inequality, \(1 < x \leq 3\), we need to show all \(x\)-values that fall strictly greater than 1 and up to and including 3.
To graph this:
- Place an open circle at 1 on the number line. This signifies \(x\) cannot be exactly 1. An open circle indicates that the endpoint is not part of the solution.
- Place a closed circle at 3, meaning \(x\) can be exactly 3. A closed circle suggests that this point is included in the solution.
- Shade the number line between 1 and 3 to show all the possible values of \(x\) between these points.
Interval Notation
Interval notation provides a concise way to denote subsets of real numbers that represent the solution to inequalities.
For the inequality \(1 < x \leq 3\), the interval notation is written as \((1, 3]\).
Here's how it works:
For the inequality \(1 < x \leq 3\), the interval notation is written as \((1, 3]\).
Here's how it works:
- The round parenthesis "(" at the beginning indicates that the endpoint \(x = 1\) is not included in the solution, corresponding to an open circle on the number line.
- The square bracket "]" at the end means that the endpoint \(x = 3\) is included, corresponding to a closed circle on the number line.
- This notation effectively communicates the range of values \(x\) can take, allowing for quick and clear interpretation of solution sets.