Chapter 2: Problem 71
Solve each inequality or compound inequality. Write the solution set in interval notation and graph it. $$ -\frac{2}{3} \geq \frac{2 y}{3}-\frac{3}{4} $$
Short Answer
Expert verified
The solution is \((-\infty, \frac{1}{8} ]\).
Step by step solution
01
Eliminate Fractions
To eliminate fractions, we will multiply every term by the least common multiple of the denominators. Here, the denominators are 3 and 4, so the least common multiple is 12. Multiply everything by 12.\(12 \left(-\frac{2}{3}\right) \geq 12 \left(\frac{2y}{3}\right) - 12 \left(\frac{3}{4}\right) \)This simplifies to:\(-8 \geq 8y - 9\)
02
Isolate the Variable Term
First, add 9 to both sides of the inequality to move the constant term on the right to the left.\(-8 + 9 \geq 8y - 9 + 9\)Simplify:\(1 \geq 8y\)This can also be written as:\(8y \leq 1\)
03
Solve for the Variable
To isolate \(y\) on one side, divide both sides by 8.\(\frac{8y}{8} \leq \frac{1}{8}\)Simplify:\(y \leq \frac{1}{8}\)
04
Write the Solution in Interval Notation
The solution \(y \leq \frac{1}{8}\) means that \(y\) can be any number less than or equal to \(\frac{1}{8}\). In interval notation, this is written as:\(( -\infty, \frac{1}{8} ]\)
05
Graph the Solution
To graph the solution \(( -\infty, \frac{1}{8} ]\), draw a number line. Locate \(\frac{1}{8}\) on the number line. Use a closed dot on \(\frac{1}{8}\) to indicate that it is included in the solution set, and shade all the area to the left of \(\frac{1}{8}\) to represent all values less than \(\frac{1}{8}\).
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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 represent a set of numbers between two endpoints. It's particularly useful when dealing with inequalities as it provides a clear and concise way to display solution sets.
For example, consider a solution set of all numbers less than or equal to \(\frac{1}{8}\). We would write this in interval notation as \(( -\infty, \frac{1}{8} ]\).
This notation includes:
For example, consider a solution set of all numbers less than or equal to \(\frac{1}{8}\). We would write this in interval notation as \(( -\infty, \frac{1}{8} ]\).
This notation includes:
- A round bracket "(" or ")" implies that the endpoint is not included.
- A square bracket "[" or "]" shows that the endpoint is included.
- The symbol \(-\infty\) always comes with a round bracket because infinity is not a number we can "reach" or include.
Compound Inequalities
Compound inequalities involve two or more simple inequalities that are combined into a single expression. You can think of them as extending the concept of regular inequalities.
There are two main types:
There are two main types:
- "And" Compound Inequalities: These require both conditions to be satisfied simultaneously. For example, \(x > -3\) and \(x \leq 5\) would intersect or "AND" to give a range \((-3, 5]\).
- "Or" Compound Inequalities: These work if at least one of the conditions is satisfied. For example, \(x < -1\) or \(x \geq 2\).
Graphing Inequalities
Graphing inequalities visually represents the solution set on a number line, adding clarity to the algebraic expression.
Steps to effectively graph an inequality like \(y \leq \frac{1}{8}\):
Steps to effectively graph an inequality like \(y \leq \frac{1}{8}\):
- Draw a horizontal line to represent the number line.
- Identify and mark the critical number, in this case, \(\frac{1}{8}\).
- Since the inequality includes \(\frac{1}{8}\), place a "closed" dot on \(\frac{1}{8}\) to show it is part of the solution set.
- Shade the region on the number line to the left of \(\frac{1}{8}\) to indicate that all numbers less than \(\frac{1}{8}\) are included.