Chapter 1: Problem 75
Solve the absolute value inequality. Express the answer using interval notation and graph the solution set. $$8-|2 x-1| \geq 6$$
Short Answer
Expert verified
The solution is \([-\frac{1}{2}, \frac{3}{2}]\).
Step by step solution
01
Simplify the Inequality
To begin with, simplify the given inequality: \[ 8 - |2x - 1| \geq 6 \]Subtract 6 from both sides to isolate the absolute value expression:\[ 8 - |2x - 1| - 6 \geq 0 \]which simplifies to:\[ 2 - |2x - 1| \geq 0 \]
02
Rewrite the Absolute Inequality
Move the absolute value term to one side of the inequality:\[ |2x - 1| \leq 2 \]This next step involves conceptualizing the inequality into two separate cases (since absolute value measures distance).
03
Case 1 - Positive Scenario
Consider the scenario where the expression inside the absolute value is non-negative:\[ 2x - 1 \leq 2 \]Solve for \( x \) by first adding 1 to both sides:\[ 2x \leq 3 \]Now, divide both sides by 2 to solve for \( x \):\[ x \leq \frac{3}{2} \]
04
Case 2 - Negative Scenario
Now consider the scenario where the expression inside the absolute value is negative, transforming the expression:\[ -(2x - 1) \leq 2 \]Simplify to:\[ -2x + 1 \leq 2 \]Subtract 1 from both sides:\[ -2x \leq 1 \]Finally, divide both sides by -2 and remember to reverse the inequality:\[ x \geq -\frac{1}{2} \]
05
Combine Solutions
The solution from both scenarios gives:\(-\frac{1}{2} \leq x \leq \frac{3}{2} \).This interval notation captures the solution set as:\[ [-\frac{1}{2}, \frac{3}{2}] \].
06
Graph the Solution Set
On a number line, graph the interval by shading between \(-\frac{1}{2}\) and \(\frac{3}{2}\), inclusive. Place solid dots (or closed circles) on \(-\frac{1}{2}\) and \(\frac{3}{2}\) to indicate that these endpoints are included in the solution set.
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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 method of writing down a set of numbers that fall within a certain range. This is particularly useful when dealing with inequalities, such as \( -\frac{1}{2} \leq x \leq \frac{3}{2} \). Interval notation helps convey this range simply and efficiently. In this specific context, our interval is written as \( [-\frac{1}{2}, \frac{3}{2}] \), where the square brackets indicate that the endpoints \(-\frac{1}{2}\) and \(\frac{3}{2}\) are included in the solution set.
When using interval notation:
When using interval notation:
- Square brackets \([ ]\) signify that the endpoints are included, also known as a closed interval.
- Parentheses \(( )\) would indicate that the endpoints are not included, implying an open interval.
Graphing Inequalities
Graphing inequalities involves visually representing the solutions to inequalities on a number line. This helps provide a clear visual indication of which numbers satisfy the inequality. For our problem, \([-\frac{1}{2}, \frac{3}{2}]\), the process consists of marking points and shading relevant areas.
To accurately graph this inequality:
To accurately graph this inequality:
- Start by placing solid dots (closed circles) at the endpoints \(-\frac{1}{2}\) and \(\frac{3}{2}\) to indicate inclusion.
- Next, shade the entire region between these two points on the number line.
Solving Inequalities
Solving inequalities is a crucial skill in algebra that involves finding all values that satisfy a particular inequality. When solving an inequality, particularly one involving an absolute value, it is important to break down the problem into manageable steps.
In our exercise:
In our exercise:
- The original inequality is \(8-|2x-1| \geq 6\). Simplify this by isolating the absolute value term, leading to \(|2x-1| \leq 2\).
- Next, consider the absolute value generates two separate scenarios: one where the inside is positive or zero, and one where it is negative.
Absolute Value
The concept of absolute value is a fundamental aspect of mathematics, showcasing the idea of distance from zero on a number line. It is always non-negative, as it represents the magnitude without considering direction. In the context of inequalities like \( |2x-1| \leq 2 \), the absolute value necessitates considering both directions from zero.
This leads to:
This leads to:
- A positive or zero case: \(2x-1 \leq 2\)
- A negative case: \(-(2x-1) \leq 2\), which simplifies further.