Chapter 8: Problem 55
Graph the solution set, and write it using interval notation. $$ 4 \leq-9 x+5<8 $$
Short Answer
Expert verified
The solution set in interval notation is \((-\frac{1}{3}, \frac{1}{9}]\).
Step by step solution
01
- Break the Compound Inequality
Separate the compound inequality into two individual inequalities: 1) \(4 \leq -9x+5\)2) \(-9x+5 < 8\)
02
- Solve the First Inequality
Or equivalently: \(x \leq \frac{1}{9}\)
03
- Solve the Second Inequality
Solve the second inequality: \(-9x + 5 < 8\)Subtract 5 from both sides: \(-9x + 5 - 5 < 8 - 5\)Simplify: \(-9x < 3\)Divide by -9 (remember to reverse the inequality sign when dividing by a negative number): \(x > \frac{3}{-9}\)This simplifies to: \(x > -\frac{1}{3}\)
04
- Combine the Solutions
Combine the solutions: \(-\frac{1}{3} < x \leq \frac{1}{9}\)
05
- Write the Solution in Interval Notation
Express the solution set in interval notation: \((-\frac{1}{3}, \frac{1}{9}]\)
06
- Graph the Solution
Graph the interval on the number line: - Open circle at \(-\frac{1}{3}\) to indicate \(x > -\frac{1}{3}\), and filled circle at \(\frac{1}{9}\) to indicate \(x \leq \frac{1}{9}\). Shade the region between them.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
solving inequalities
Inequalities express a relationship where one side is not necessarily equal to the other side. In algebra, solving inequalities involves finding the values of a variable that make the inequality true. Let's break down the steps to solve the compound inequality given: \( 4 \leq -9x + 5 < 8 \).
- First, you split the compound inequality into two separate inequalities: \(4 \leq -9x + 5 \) and \(-9x + 5 < 8 \).
- Then, solve each part individually. For \( 4 \leq -9x + 5 \):
1. Subtract 5 from both sides to get: \( -1 \leq -9x \).
2. Divide by -9 (note: reversing the inequality sign): \( x \leq \frac{1} {9} \). - Similarly, for \( -9x + 5 < 8 \):
1. Subtract 5 from both sides: \( -9x < 3 \).
2. Divide by -9 (note: reversing the inequality sign): \( x > -\frac{1}{3} \). - Finally, combine the two solutions to get \( -\frac{1}{3} < x \leq \frac{1}{9} \).
interval notation
Interval notation is a way of writing sets of numbers that fall within a certain range. It uses brackets and parentheses to describe the endpoints of an interval. For example, \( [a, b] \) includes endpoints \(a\) and \(b\), whereas \( (a, b) \) excludes them.
In this exercise, the solution \( -\frac{1}{3} < x \leq \frac{1}{9} \) needs to be written in interval notation.
In this exercise, the solution \( -\frac{1}{3} < x \leq \frac{1}{9} \) needs to be written in interval notation.
- We use a parenthesis \((\) to indicate that \( -\frac{1}{3}\) is not included in the solution.
- We use a bracket \(] \) to show that \( \frac{1}{9} \) is included in the solution.
- Therefore, the interval notation for the solution is \( ( -\frac{1}{3}, \frac{1}{9}] \).
- This interval notation tells us exactly where the solutions for the inequality lie on a number line.
graphing solutions
Graphing the solution of an inequality involves drawing it on a number line to visually represent the range of possible solutions. Here’s how to graph the given solution:\( ( -\frac{1}{3}, \frac{1}{9} ] \)
This visual graph makes it easier to understand the solution set and clearly shows the range of numbers that satisfy the inequality.
- Plot a number line marking key points, specifically \( -\frac{1}{3} \) and \( \frac{1}{9} \).
- Use an open circle on \( -\frac{1}{3} \) to indicate that \( -\frac{1}{3} \) is not part of the solution (because we use \( < \), not \( \leq\)).
- Use a filled circle on \( \frac{1}{9} \) to show that \( \frac{1}{9} \) is included in the solution (due to \( \leq \)).
- Shade the region between \( -\frac{1}{3} \) and \( \frac{1}{9} \) to represent all values that \( x \) can take.
This visual graph makes it easier to understand the solution set and clearly shows the range of numbers that satisfy the inequality.