Chapter 1: Problem 45
Solve each inequality. Express your answer using set notation or interval notation. Graph the solution set. $$ |2 x-3| \geq 2 $$
Short Answer
Expert verified
The solution set is \( ( - \infty,1/2 ] \cup [ 5/2, \infty ) \).
Step by step solution
01
Understand the Absolute Value Inequality
The inequality is \(|2x - 3| \geq 2\). Recall that for an absolute value inequality of the form \(|A| \geq B\), it translates to two separate inequalities: \(A \geq B\) and \(A \leq -B\).
02
Split the Inequality
Write the two separate inequalities for \(|2x - 3| \geq 2\). Thus, \(2x - 3 \geq 2\) and \(2x - 3 \leq -2\).
03
Solve the First Inequality
Solve \(2x - 3 \geq 2\). Add 3 to both sides: \(2x \geq 5\). Then, divide both sides by 2: \(x \geq 5/2\).
04
Solve the Second Inequality
Solve \(2x - 3 \leq -2\). Add 3 to both sides: \(2x \leq 1\). Then, divide both sides by 2: \(x \leq 1/2\).
05
Combine the Solutions
Combine the solutions from Step 3 and Step 4. You get \(x \geq 5/2\) or \(x \leq 1/2\).
06
Express in Interval Notation
The solution set in interval notation is \((\infty, 1/2] \cup [5/2, \infty)\).
07
Graph the Solution Set
On a number line, shade all the values starting from negative infinity up to and including 1/2. Also, shade all the values starting from 5/2 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 Inequalities
Absolute value inequalities are a bit of a mouthful, but let's break them down into simpler terms. The absolute value of a number is its distance from zero on the number line, regardless of direction. Hence, when you see something like \( |2x - 3| \geq 2 \), it means that the expression inside the absolute value is either greater than or equal to 2, or less than or equal to -2.
So, we split \( |2x - 3| \geq 2 \) into two separate inequalities: \[ 2x - 3 \geq 2 \] and \[ 2x - 3 \leq -2 \]. Solving each inequality gives you the set of solutions that make the original absolute value inequality true. Remember:
So, we split \( |2x - 3| \geq 2 \) into two separate inequalities: \[ 2x - 3 \geq 2 \] and \[ 2x - 3 \leq -2 \]. Solving each inequality gives you the set of solutions that make the original absolute value inequality true. Remember:
- The first inequality, \[ 2x - 3 \geq 2 \], simplifies to \[ x \geq 5/2 \].
- The second inequality, \[ 2x - 3 \leq -2 \], simplifies to \[ x \leq 1/2 \].
Interval Notation
Interval notation is a shorthand way to describe the set of solutions to an inequality. It's a compact, elegant way to express ranges of numbers without writing out long inequalities.
For our inequalities, we ended up with two simple expressions: \[ x \geq 5/2 \] or \[ x \leq 1/2 \].
In interval notation, these solutions look like this:
Notice the brackets and parentheses: Use a square bracket \( [ \) or \( ] \) when the endpoint is included in the set and use a parenthesis \( ( \) or \( ) \) when it's not.
For our inequalities, we ended up with two simple expressions: \[ x \geq 5/2 \] or \[ x \leq 1/2 \].
In interval notation, these solutions look like this:
- The values of x that are less than or equal to \[ 1/2 \] are written as \[ (-\infty , \ 1/2] \].
- The values of x that are greater than or equal to \[ 5/2 \] are written as \[ [5/2 , \ \infty) \].
Notice the brackets and parentheses: Use a square bracket \( [ \) or \( ] \) when the endpoint is included in the set and use a parenthesis \( ( \) or \( ) \) when it's not.
Graphing Inequalities
Graphing inequalities on a number line helps to visually understand the solution set. Here's how you do it:
1. Draw a number line with enough points to mark your critical numbers (like \( 1/2 \) and \( 5/2 \) in our problem).
2. For \[ x \leq 1/2 \], plot a closed dot on \[ 1/2 \] (because 1/2 is included in the solution set) and draw a line extending to the left, towards negative infinity.
3. For \[ x \geq 5/2 \], plot a closed dot on \[ 5/2 \] (because 5/2 is included in the solution set) and draw a line extending to the right, towards positive infinity.
This effectively shows that all values less than or equal to \[ 1/2 \] and greater than or equal to \[ 5/2 \] satisfy the original inequality \[ |2x - 3| \geq 2 \]. The graph becomes very handy when you are dealing with more complex inequalities or systems of inequalities.
1. Draw a number line with enough points to mark your critical numbers (like \( 1/2 \) and \( 5/2 \) in our problem).
2. For \[ x \leq 1/2 \], plot a closed dot on \[ 1/2 \] (because 1/2 is included in the solution set) and draw a line extending to the left, towards negative infinity.
3. For \[ x \geq 5/2 \], plot a closed dot on \[ 5/2 \] (because 5/2 is included in the solution set) and draw a line extending to the right, towards positive infinity.
This effectively shows that all values less than or equal to \[ 1/2 \] and greater than or equal to \[ 5/2 \] satisfy the original inequality \[ |2x - 3| \geq 2 \]. The graph becomes very handy when you are dealing with more complex inequalities or systems of inequalities.