Chapter 9: Problem 55
Graph the solution set of each system of inequalities. $$\begin{aligned}&y \leq \log x\\\&y \geq|x-2|\end{aligned}$$
Short Answer
Expert verified
Graph the regions \( y \leq \log x \) and \( y \geq |x-2| \), and find the overlapping area.
Step by step solution
01
Understand the Inequalities
The first inequality is \( y \leq \log x \) which represents all points \(x, y\) that lie on or below the curve of the logarithmic function \( y = \log x \). The second inequality is \( y \geq |x - 2| \) which represents all points \(x, y\) that lie on or above the line of the absolute value function \( y = |x - 2| \).
02
Graph the First Inequality
Graph the equation \( y = \log x \), typically starting at \( x = 1 \) where \( y = 0 \). The graph should be below this line. Shade the region below this curve since \( y \leq \log x \).
03
Graph the Second Inequality
Graph the equation \( y = |x - 2| \). This consists of two rays: one starting from the vertex at \( x = 2 \) and \( y = 0 \), going to the left where \( y = 2 - x \), and the other going to the right where \( y = x - 2 \). Shade the region above this V-like shape because \( y \geq |x - 2| \).
04
Find the Overlapping Region
Combine the two shaded regions: one from Step 2 and one from Step 3. The solution set to the system of inequalities is the region where the shaded areas overlap. This area represents points that satisfy both \( y \leq \log x \) and \( y \geq |x-2| \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Graphing Inequalities
Graphing inequalities involves plotting regions on a coordinate plane that satisfy the given inequality. Inequalities describe a range of values rather than exact points. To graph an inequality, you follow these steps:
1. Graph the boundary line or curve. The inequality symbol determines if you need a solid line (≤ or ≥) or a dashed line (< or >).
2. Determine which side of the boundary the inequality covers by selecting a test point and substituting it into the inequality.
3. Shade the region containing all the points that satisfy the inequality.
For instance, in the inequality system given in the exercise:
1. Graph the boundary line or curve. The inequality symbol determines if you need a solid line (≤ or ≥) or a dashed line (< or >).
2. Determine which side of the boundary the inequality covers by selecting a test point and substituting it into the inequality.
3. Shade the region containing all the points that satisfy the inequality.
For instance, in the inequality system given in the exercise:
- For the inequality **y ≤ log x**, you graph the curve of the logarithmic function **y = log x** and shade below the curve.
- For the inequality **y ≥ |x - 2|**, you plot the V-shaped absolute value function **y = |x - 2|** and shade above this V-shape.
Logarithmic Functions
Logarithmic functions are essential in understanding exponential growth and decay. The function **y = log x** has some unique properties:
1. The logarithm base is usually 10 (common logarithm) or e (natural logarithm). When not specified, we often assume the base of 10.
2. The curve **y = log x** passes through the point **(1, 0)** because **log(1) = 0**.
3. For values **x > 1**, **y = log x** is positive, and for **0 < x < 1**, **y = log x** is negative.
When graphing logarithmic inequalities like **y ≤ log x**, remember:
1. The logarithm base is usually 10 (common logarithm) or e (natural logarithm). When not specified, we often assume the base of 10.
2. The curve **y = log x** passes through the point **(1, 0)** because **log(1) = 0**.
3. For values **x > 1**, **y = log x** is positive, and for **0 < x < 1**, **y = log x** is negative.
When graphing logarithmic inequalities like **y ≤ log x**, remember:
- The function only exists for **x > 0**.
- **y** values become negative as **x** approaches 0 from the right and grow larger as **x** increases.
- When shading for **y ≤ log x**, you shade all the area below the curve of **y = log x**.
Absolute Value Functions
Absolute value functions depict distances and always produce non-negative results. The standard form is **y = |x - h|**, where **h** is a horizontal shift. To graph **y = |x - 2|**, follow these guidelines:
1. Identify the vertex of the absolute value function, which will be at **(2, 0)** for **y = |x - 2|**.
2. Recognize the V-shape centered at the vertex. For **x > 2**, the function grows linearly with a slope of 1 (**y = x - 2**), and for **x < 2**, it decreases linearly (**y = 2 - x**).
When dealing with the inequality **y ≥ |x - 2|**:
1. Identify the vertex of the absolute value function, which will be at **(2, 0)** for **y = |x - 2|**.
2. Recognize the V-shape centered at the vertex. For **x > 2**, the function grows linearly with a slope of 1 (**y = x - 2**), and for **x < 2**, it decreases linearly (**y = 2 - x**).
When dealing with the inequality **y ≥ |x - 2|**:
- Graph the boundary line **y = |x - 2|** with a solid line since the inequality includes equal to (≥).
- Shade the region above the V-shape because **y** values are greater than or equal to the absolute value function.