Chapter 8: Problem 97
Solve each inequality. Graph the solution set and write it in interval notation. $$ 0.4 x+0.4 \leq 0.1 x+0.85 $$
Short Answer
Expert verified
The solution is \((-\infty, 1.5]\).
Step by step solution
01
Rearrange the Inequality
We start with the inequality: \[0.4x + 0.4 \leq 0.1x + 0.85\]To isolate the term with \(x\) on one side, we subtract \(0.1x\) from both sides:\[0.4x - 0.1x + 0.4 \leq 0.85\]
02
Simplify the Expression
Let's simplify the expression obtained:\[0.3x + 0.4 \leq 0.85\]Now, subtract \(0.4\) from both sides to isolate the term with \(x\):\[0.3x \leq 0.85 - 0.4\]
03
Solve for x
Calculate the difference on the right side:\[0.3x \leq 0.45\]Now, divide both sides by \(0.3\) to solve for \(x\):\[x \leq \frac{0.45}{0.3}\]
04
Calculate the Division
Compute the division on the right side:\[x \leq 1.5\]
05
Graph the Solution
On a number line, draw a solid line from negative infinity to \(1.5\), and place a closed dot on \(1.5\) because \(x\leq1.5\) includes \(1.5\) itself.
06
Write in Interval Notation
The solution set in interval notation is:\[(-\infty, 1.5]\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Inequality Notation
Inequalities are a way to express the relationship between two values when they are not equal. The inequality sign provides a variety of ways to express how one value compares to another. Here are some key inequality symbols:
- \( < \) : Less than
- \( \leq \) : Less than or equal to
- \( > \) : Greater than
- \( \geq \) : Greater than or equal to
Interval Notation
Interval notation is a concise way of writing an interval of numbers instead of using an inequality. It provides an easy method to represent sets of solutions. Here's a breakdown of symbols in interval notation:
- \((a, b)\): Represents all numbers between \(a\) and \(b\), not including \(a\) and \(b\).
- \([a, b]\): Includes all numbers between \(a\) and \(b\), and includes \(a\) and \(b\) themselves.
- \((a, b]\): Includes all numbers between \(a\) and \(b\), but not \(a\).
- \([a, b)\): Includes all numbers between \(a\) and \(b\), but not \(b\).
Graphing Inequalities
Graphing inequalities on a number line helps visualize their solutions. This process involves marking specific points and shading the regions representing all possible solutions. Here's how you can graph an inequality such as \( x \leq 1.5 \):- Start by drawing a number line.- Find 1.5 on this line.- Place a closed dot on 1.5 because the inequality includes this number (due to the \( \leq \) sign).- Shade the line to the left of 1.5 to represent all numbers less than 1.5.- The shaded region along with the closed dot signifies the solution set.By viewing a graph, you can instantly see which values satisfy the inequality, providing a powerful visual tool in problem-solving.