Chapter 2: Problem 83
Solve each inequality or compound inequality. Write the solution set in interval notation and graph it. $$ y-\frac{1}{7} \leq \frac{2}{3} $$
Short Answer
Expert verified
The solution is \((-\infty, \frac{17}{21}]\).
Step by step solution
01
Isolate the variable
To solve the inequality \( y - \frac{1}{7} \leq \frac{2}{3} \), we need to isolate \( y \). Start by adding \( \frac{1}{7} \) to both sides of the inequality to undo the subtraction. This gives us: \[ y \leq \frac{2}{3} + \frac{1}{7} \].
02
Find common denominator
To combine the fractions \( \frac{2}{3} \) and \( \frac{1}{7} \), we need a common denominator. The least common multiple of 3 and 7 is 21. Convert the fractions to have this denominator: \( \frac{2}{3} = \frac{14}{21} \) and \( \frac{1}{7} = \frac{3}{21} \).
03
Add the fractions
Now add the fractions \( \frac{14}{21} + \frac{3}{21} \). This results in \( \frac{17}{21} \). Translated to the inequality, we have: \[ y \leq \frac{17}{21} \].
04
Express solution in interval notation
The solution to the inequality \( y \leq \frac{17}{21} \) can be expressed in interval notation. Since \( y \) can take any value less than or equal to \( \frac{17}{21} \), the interval is \((-\infty, \frac{17}{21}]\).
05
Graph the solution
On a number line, plot the solution. Draw a solid dot at \( \frac{17}{21} \) to indicate that this value is included in the solution. Then, shade the line to the left of this point to indicate all values less than \( \frac{17}{21} \) are part of the solution.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Interval Notation
When solving inequalities, interval notation is a concise way to express all possible solutions. It uses brackets and parentheses to indicate which numbers are part of the solution. In our exercise, the inequality solution was \( y \leq \frac{17}{21} \).
To express this in interval notation, we needed to show all the values \( y \) can take, which are any numbers less than or equal to \( \frac{17}{21} \).
To express this in interval notation, we needed to show all the values \( y \) can take, which are any numbers less than or equal to \( \frac{17}{21} \).
- A bracket \([a, b]\) indicates that both \(a\) and \(b\) are included in the solution.
- A parenthesis \((a, b)\) means \(a\) and \(b\) are not included.
Common Denominator
Finding a common denominator is crucial when you need to add or compare fractions. In our inequality, before we could find the solution, we had to handle two fractions: \( \frac{2}{3} \) and \( \frac{1}{7} \).
These fractions need a common denominator to be combined. Here's how you do it:
These fractions need a common denominator to be combined. Here's how you do it:
- Identify the denominators you are working with — here, they are 3 and 7.
- Determine the least common multiple (LCM) of the denominators. For 3 and 7, this is 21.
- Convert each fraction to an equivalent fraction with the common denominator.\[ \frac{2}{3} \to \frac{14}{21} \text{ and } \frac{1}{7} \to \frac{3}{21} \]
Number Line Graphing
Graphing inequalities visually shows the solution set on a number line. It's especially useful in seeing the range of values included in the solution.
In the exercise, after solving the inequality and writing \( y \leq \frac{17}{21} \), we needed to graph it on a number line.
In the exercise, after solving the inequality and writing \( y \leq \frac{17}{21} \), we needed to graph it on a number line.
- Locate \( \frac{17}{21} \) on the number line.
- Draw a solid dot at \( \frac{17}{21} \) to signify that this endpoint is included in the solution.
- Shade the number line to the left of this point, indicating all values less than \( \frac{17}{21} \) are solutions.