Chapter 3: Problem 40
Solve and write interval notation for the solution set. Then graph the solution set. $$|x| \geq 2$$
Short Answer
Expert verified
The solution set in interval notation is \((-\infty, -2] \cup [2, \infty)\). Graph it with closed dots at -2 and 2, shading left from -2 and right from 2.
Step by step solution
01
Understand the Absolute Value Inequality
The inequality \(|x| \geq 2\) means that the distance of \(x\) from 0 is greater than or equal to 2. This gives us two separate inequalities to solve: \(x \geq 2\) and \(x \leq -2\).
02
Solve the Inequality \(x \geq 2\)
The first part of the inequality is already simple: \(x \geq 2\). This inequality means that \(x\) can be any value starting from 2 and increasing to infinity.
03
Solve the Inequality \(x \leq -2\)
The second part of the inequality states: \(x \leq -2\). This inequality means that \(x\) can be any value starting from -2 and decreasing to negative infinity.
04
Combine the Solutions
Combining the solutions from Step 2 and Step 3, the solution set for the inequality \(|x| \geq 2\) is \(x \in (-\infty, -2] \cup [2, \infty)\).
05
Write the Solution in Interval Notation
The interval notation for the solution is \((-\infty, -2] \cup [2, \infty)\). This means \((-\infty, -2]\) union \([2, \infty)\).
06
Graph the Solution Set
To graph the solution set on a number line, place a closed dot at -2 and shade to the left to negative infinity. Then, place a closed dot at 2 and shade to the right to positive infinity.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
absolute value
The absolute value concept measures the distance a number is from zero on a number line. Absolute value is always positive because distance is never negative. For any real number, say \(x\), the absolute value is denoted as \(|x|\). Here are some key points about absolute value:
- \(|x| = x\) if \(x \geq 0\) (non-negative numbers)
- \(|x| = -x\) if \(x < 0\) (negative numbers).
inequalities
Inequalities are statements that show the relative size or order of two values. In our case, the inequality \( |x| \geq 2 \) means x must be at least 2 units away from zero.
- \(|x| \geq 2\) is split into \(x \geq 2\) and \(x \leq -2\), because absolute value measures distance from zero.
- \(>\): Greater than
- \(<\): Less than
- \(eq\): Not equal to
interval notation
Interval notation is a way to describe sets of numbers along a number line. It uses parentheses and brackets to show where the set starts and ends.
- Parentheses \( ( ) \) indicate that the endpoint is not included, meaning the value is less than or greater than but not equal.
- Brackets \( [ ] \) indicate the endpoint is included, meaning it is less than or equal to or greater than or equal to.
graphing inequalities
Graphing inequalities on a number line helps visualize solutions. To graph \(|x| \geq 2\), follow these steps:
- Mark points \(-2\) and \2\ on the number line.
- Place closed dots at these points to include them in the solution (indicated by \( \leq \) or \( \geq \)).
- Shade the line to the left of \(-2\) to show all values less than or equal to \(-2\).
- Shade the line to the right of \2\ to show all values greater than or equal to \2\.