Chapter 1: Problem 15
Linear Inequalities Solve the linear inequality. Express the solution using interval notation and graph the solution set. $$2 x-5 > 3$$
Short Answer
Expert verified
Solution: \((4, \infty)\); open circle at 4, shade right.
Step by step solution
01
Isolate the Variable
To solve the inequality, start by isolating the variable term. The inequality given is \(2x - 5 > 3\). Add 5 to both sides to remove the constant from the left side, resulting in \(2x > 8\).
02
Solve for x
Next, divide both sides by 2 to solve for \(x\). This gives \(x > 4\).
03
Express in Interval Notation
The solution to the inequality \(x > 4\) can be expressed in interval notation as \((4, \infty)\).
04
Graph the Solution Set
To graph the solution set, draw a number line. Place an open circle at 4 (since 4 is not included) and shade the line to the right of 4 to indicate all numbers greater than 4.
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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 way of writing subsets of the real numbers on a number line. It is especially useful when conveying the solution to inequalities like the one we're dealing with here. In essence, it uses a combination of numbers and round or square brackets to describe intervals.
For example, in the inequality solution, we have a simple statement:
For example, in the inequality solution, we have a simple statement:
- The inequality is: \( x > 4 \).
- This is represented in interval notation as: \((4, \infty)\).
- The number 4 is a boundary, meaning the interval starts just beyond it. We show this by using an open parenthesis, \(( \), indicating that 4 is not part of the solution.
- We write \( \infty \) (infinity) to say the interval extends indefinitely in the positive direction.
- Open intervals use \(( \text{or} )\) to show numbers not included in the set. Closed intervals use \([ \text{or} ]\), indicating numbers are included, e.g., \([a, b]\) includes both \(a\) and \(b\).
Solving Inequalities
Solving inequalities is somewhat like solving equations, but with an important difference: inequality signs can change direction. This is particularly true when multiplying or dividing by a negative number.
In our example, the inequality problem is given as:
In our example, the inequality problem is given as:
- Start with: \(2x - 5 > 3\)
- First, isolate \(x\) by adding 5 to both sides: \(2x > 8\)
- Divide both sides by 2: \(x > 4\)
- If you multiply or divide by a negative number, flip the inequality sign.
- The goal is to isolate the variable on one side of the inequality.
- It's often helpful to re-check your steps to ensure each transformation is valid under inequality rules.
Graphing Solutions
Graphing solutions is a vital step to visualize the answer of an inequality. It involves plotting the solution on a number line to make the solution set clear. This pictorial representation helps in understanding exactly which numbers satisfy the inequality.
To graph the solution \(x > 4\) of our inequality:
To graph the solution \(x > 4\) of our inequality:
- Draw a straight horizontal line to represent a number line.
- Mark the point 4 on this line. Because the inequality is "greater than" and not "equal to," use an open circle at 4.
- Shade the line to the right of 4 to indicate all numbers larger than 4 are solutions.
- The open circle at 4 specifically shows that while our numbers get close to 4, 4 itself is not included.
- The shaded part extends infinitely to the right, communicating that there is no upper bound to the values that \(x\) can take.