Chapter 2: Problem 70
Solve and graph the solution set. In addition, present the solution set in interval notation. $$ -4 \leq-13(3 x+12)<4 $$
Short Answer
Expert verified
The solution set is \((-\frac{160}{39}, -\frac{152}{39}]\), in interval notation: \((-4.10, -3.90]\).
Step by step solution
01
Break Down the Double Inequality
The given inequality is \[-4 \leq -13(3x+12) < 4\].This means you have two inequalities that you need to solve separately: 1. \(-4 \leq -13(3x+12)\)2. \(-13(3x+12) < 4\).
02
Solve the First Inequality
Solve \(-4 \leq -13(3x+12)\).First, distribute the \(-13\) into the parenthesis:\(-4 \leq -39x - 156\).Add 156 to both sides:\(152 \leq -39x\).Divide both sides by \(-39\), remembering to reverse the inequality:\(- \frac{152}{39} \geq x\).Approximate \(- \frac{152}{39} \approx -3.90\).
03
Solve the Second Inequality
Now solve \(-13(3x+12) < 4\).Distribute the \(-13\) into the parenthesis:\(-39x - 156 < 4\).Add 156 to both sides:\(-39x < 160\).Divide both sides by \(-39\), remembering to reverse the inequality:\(x > -\frac{160}{39}\).Approximate \(-\frac{160}{39} \approx -4.10\).
04
Combine the Inequality Solutions
Combine the results from Step 2 and Step 3: \(-\frac{160}{39} < x \leq -\frac{152}{39}\).This represents the solution set in inequality notation.
05
Express Solution in Interval Notation
The solution set can be expressed as an interval by using the values found:\((-\frac{160}{39}, -\frac{152}{39}]\).And approximately:\((-4.10, -3.90]\).
06
Graph the Solution
To graph, plot on a number line:- Draw an open circle at approximately \(-4.10\) to indicate that it is not included in the set.- Draw a closed circle at approximately \(-3.90\) to indicate that it is included in the set.- Shade the region between the two points to represent all the numbers that satisfy the inequality.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Solution Set
A **solution set** is a collection of all the values that satisfy a given inequality. In this exercise, the inequality is split into two separate parts to find the values of \(x\) that make it true:
- For \(-4 \leq -13(3x+12)\), the solution is \(x \leq -\frac{152}{39}\).
- For \(-13(3x+12) < 4\), the solution is \(x > -\frac{160}{39}\).
Interval Notation Described
When we use **interval notation**, we're presenting the solution set as a range of values. This notation helps articulate precisely where numbers fall in relation to each other, especially:
- Brackets \([\ ]\) indicate a number is included in the set.
- Parentheses \((\ )\) indicate a number is not included.
- \((-\frac{160}{39}\) shows \(-\frac{160}{39}\) is excluded.
- \([-\frac{152}{39}]\) means \(-\frac{152}{39}\) is included.
Visualizing with the Number Line
A **number line** is a great tool to visually represent the solution set. It makes it clear and straightforward:
Shade the line between these two points to represent all the values that satisfy the inequality.
- Identify \(-4.10\) (for \(-\frac{160}{39}\)) and place an open circle there.
- Locate \(-3.90\) (for \(-\frac{152}{39}\)) and place a closed circle there.
Shade the line between these two points to represent all the values that satisfy the inequality.
Graphing the Solution Set
**Graphing** is the process of plotting values that satisfy the inequality on a number line. Here's how to accomplish this:
- Draw a straight horizontal line to act as the number line.
- Mark \(-4.10\) with an open circle because it is not part of the solution set.
- Mark \(-3.90\) with a closed circle as it is included in the solution set.
- Shade the area between the open and closed circles.