Chapter 2: Problem 109
Graph all solutions on a number line and provide the corresponding interval notation. $$ x<5 \text { or } x \geq 15 $$
Short Answer
Expert verified
The solution is \((-
fty, 5) \cup [15,
fty)\).
Step by step solution
01
Identify Inequalities
Look at the inequalities separately. The first inequality is \( x < 5 \) and the second is \( x \geq 15 \). These will guide us in determining which parts of the number line to highlight.
02
Graph \( x < 5 \) on the Number Line
For \( x < 5 \), draw a number line and create an open circle on 5 to indicate that 5 is not included. Shade everything to the left of 5 to indicate that all numbers less than 5 are part of the solution.
03
Graph \( x \geq 15 \) on the Number Line
For \( x \geq 15 \), draw a number line and create a closed circle at 15 to indicate inclusion. Shade everything to the right of 15, including 15.
04
Combine Graphs on the Number Line
Combine the shaded regions from \( x < 5 \) and \( x \geq 15 \) onto one number line. The parts of the number line less than 5 and greater than or equal to 15 are the solution areas.
05
Write Interval Notation
The interval notation for \( x < 5 \) is \((-fty, 5)\) and for \( x \geq 15 \) is \([15, fty)\). Combine these intervals to express the complete solution: \((-fty, 5) \cup [15, fty)\).
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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 handy way to express the set of solutions for an inequality. It's all about visually capturing the start and end of a range.
For the inequality \(x < 5\), you use an open parenthesis \((-\infty, 5)\) because 5 is not included in the solution set. The open parenthesis signifies that the endpoint is not part of the interval.
For \(x \geq 15\), a closed bracket \([15, \infty)\) is used, as 15 is included in the solution.
For the inequality \(x < 5\), you use an open parenthesis \((-\infty, 5)\) because 5 is not included in the solution set. The open parenthesis signifies that the endpoint is not part of the interval.
For \(x \geq 15\), a closed bracket \([15, \infty)\) is used, as 15 is included in the solution.
- Open parentheses \((\) are used when the number itself is not part of the solution.
- Closed brackets \([\) signify that the number is included.
Number Line
A number line is a simple yet powerful tool to visualize inequalities. It allows you to quickly understand which numbers lie within a certain range. For \(x < 5\), place an open circle at 5 and shade everything left of it. This shows none of the shaded numbers include 5, capturing the essence of "less than".
For \(x \geq 15\), use a closed circle at 15 and shade everything to the right, indicating 15 is part of the solution.
For \(x \geq 15\), use a closed circle at 15 and shade everything to the right, indicating 15 is part of the solution.
- An open circle implies the number is not included (e.g., \(x < 5\)).
- A closed circle implies inclusion (e.g., \(x \geq 15\)).
Graphing Inequalities
Graphing inequalities on a number line is a way of translating algebraic expressions into visual formats. This makes it easier to identify solution sets.For the inequality \(x < 5\), drawing it involves placing an open circle at 5, shading everything left to show all numbers less than 5 are included. For \(x \geq 15\), a closed circle at 15 with shading to the right shows inclusion of 15 and everything greater.
- Graphs help in identifying overlapping or separate solutions.
- They visually display the range of possible solutions for any given inequality.