Chapter 8: Problem 72
Solve each compound inequality, if possible. Graph the solution set (if one exists) and write it using interval notation. $$ x \leq 6-\frac{1}{2} x \text { and } \frac{1}{2} x+1 \geq 3 $$
Short Answer
Expert verified
The solution set is \( [4, 4] \), and it represents just the point \( x = 4 \).
Step by step solution
01
Solve the First Inequality
The first inequality given is \( x \leq 6 - \frac{1}{2}x \). To solve for \( x \), first add \( \frac{1}{2}x \) to both sides:\[ x + \frac{1}{2}x \leq 6 \]This simplifies to:\[ \frac{3}{2}x \leq 6 \]Next, divide both sides by \( \frac{3}{2} \) to isolate \( x \):\[ x \leq \frac{6}{\frac{3}{2}} = 6 \times \frac{2}{3} = 4 \]Thus, the solution to the first inequality is \( x \leq 4 \).
02
Solve the Second Inequality
The second inequality is \( \frac{1}{2}x + 1 \geq 3 \). Begin by subtracting 1 from both sides:\[ \frac{1}{2}x \geq 2 \]Now, multiply both sides by 2 to solve for \( x \):\[ x \geq 4 \]Thus, the solution to the second inequality is \( x \geq 4 \).
03
Combine the Solutions
We need to find values of \( x \) that satisfy both inequalities simultaneously. From Step 1, we have \( x \leq 4 \), and from Step 2, we have \( x \geq 4 \). The overlap or intersection of these solutions is \( x = 4 \).
04
Graph the Solution
On a number line, draw a closed dot on \( x = 4 \) to indicate that 4 is included. There are no other values satisfying both inequalities, so the graph is just a single point, \( x = 4 \).
05
Write the Solution in Interval Notation
The solution is just the number 4 itself. In interval notation, this is represented as \([4, 4]\), indicating the single point at 4.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Solving Inequalities
Inequalities are mathematical expressions that involve a comparison between two values using symbols like \(<, \leq, >, \geq\). Solving inequalities means finding the set of values that makes the inequality true. Here's a friendly guide on how to tackle compound inequalities like the ones in our exercise.
- Step-by-Step Approach: Break down the compound inequality into two separate inequalities. In our problem, we have:
- \( x \leq 6 - \frac{1}{2}x \)
- \( \frac{1}{2}x + 1 \geq 3 \)
- Simplifying Each Inequality: For the first inequality, add \( \frac{1}{2}x \) to both sides to isolate \( x \), and for the second inequality, simplify by solving for \( x \).
- Combining Results: Once each inequality is solved, merge the solutions to find the common values. This gives you the values that satisfy the entire compound inequality.
Interval Notation
Interval notation is a shorthand way of writing solutions to inequalities. It's particularly useful because it allows you to illustrate the range of values that your solution covers.
- Understanding the Symbols: In interval notation, square brackets \([ ]\) are used when the endpoints are included, indicating 'closed' intervals. Parentheses \(( )\) are used when they aren't included, indicating 'open' intervals.
- Applying this to the Exercise: For our compound inequality, the solution after combining is just one point: \( x = 4 \). This means the interval notation is a closed interval, \([4, 4]\).
- Benefits of Interval Notation: It provides an easy-to-read structure that communicates exactly which numbers are part of the solution. It helps quickly convey complex mathematical concepts.
Graphing Solutions
Graphing the solutions of an inequality on a number line helps visualize the set of possible answers. It's a simple way to ensure your solution makes intuitive sense.
- Using a Number Line: Place a number line on your paper, and use dots or shading to indicate the solution set. A filled-in circle shows inclusion of the endpoint, while an open circle indicates it’s not included.
- Our Graph for \( x = 4 \): Since our solution set \( x = 4 \) includes the number 4, we place a solid dot on the number line at \( x = 4 \). This visually clarifies to anyone that this is the exact solution point.
- Importance of Graphing: Graphing not only aids visual learners but also reinforces confidence in the solution by providing an immediate check if it aligns with the mathematical solution.