Chapter 1: Problem 24
Solve the inequality. Express the answer using interval notation. $$ |x-9|>9 $$
Short Answer
Expert verified
The solution is \((-\infty, 0) \cup (18, \infty)\).
Step by step solution
01
Understand the Absolute Value Inequality
The inequality \(|x-9| > 9\) implies that the distance of \(x\) from 9 is greater than 9. This means \(x\) could be either more than 9 units away positively or more than 9 units away negatively.
02
Break Into Two Inequalities
Since \(|x-9| > 9\), we can split this into two separate inequalities: 1. \(x - 9 > 9\) 2. \(x - 9 < -9\).
03
Solve the First Inequality
For the inequality \(x - 9 > 9\), solve for \(x\):\[ x - 9 > 9 \]Add 9 to both sides:\[ x > 18 \].
04
Solve the Second Inequality
For the inequality \(x - 9 < -9\), solve for \(x\):\[ x - 9 < -9 \]Add 9 to both sides:\[ x < 0 \].
05
Combine Solutions Using Interval Notation
The solutions to the inequalities \(x > 18\) and \(x < 0\) are combined using the union of two intervals:\((-\infty, 0) \cup (18, \infty)\).
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Interval Notation
Interval notation is a shorthand used in mathematics to show the set of all solutions to an inequality. This notation uses brackets and parentheses to depict ranges of numbers without listing every individual solution.
- Use parentheses, \((\), when a number is not included in the set. For example, \((0, 1)\) includes all the numbers between 0 and 1 but not 0 and 1 themselves.
- Use brackets, \([\), when a number is included in the set. For example, \([0, 1]\) includes 0, 1, and all numbers between them.
Solving Inequalities
Solving inequalities involves finding the set of numbers that make the inequality true. Inequalities like \(|x-9|>9\) describe a range of answers rather than just one solution. To solve absolute value inequalities, the process often involves splitting the absolute value expression into two separate inequalities. For \(|x-9|>9\), think of it as a boundary problem, where you're finding when the expression inside the absolute value is further away from zero than 9. This splits into two cases:
- One where \((x - 9) > 9\)
- Another where \((x - 9) < -9\)
- \(x - 9 > 9\) simplifies to \(x > 18\) by adding 9 to both sides.
- \(x - 9 < -9\) simplifies to \(x < 0\) by adding 9 to both sides.
Distance on the Number Line
Understanding absolute value in terms of distance on the number line can simplify many problems.
- The absolute value \(|x-9|\) represents the distance of \(x\) from 9.
- If \(|x-9| > 9\), it means that \(x\) is more than 9 units away from the point 9 either to the left or right on the number line.