Chapter 3: Problem 19
For the following exercises, graph the given functions by hand. $$ y=|x|-2 $$
Short Answer
Expert verified
Graph the V-shaped function \(y=|x|-2\) with vertex at (0,-2).
Step by step solution
01
Understand the Basic Graph
The basic graph we will draw here is for the function \(y = |x|\). This is a V-shaped graph that has a vertex or a point at the origin (0,0). It opens upwards with two parts: the right part is the line \(y = x\) and the left part is the line \(y = -x\).
02
Apply the Transformation
The function given is \(y = |x| - 2\). This is the absolute value function \(y = |x|\) shifted downward by 2 units. So, take the entire graph of \(y = |x|\) and move every point on the graph 2 units down.
03
Plot Key Points
Begin by plotting the vertex of the transformed graph at (0, -2), since it was moved down 2 units. Then plot additional points. For example, for x = 1, y = 1-2 = -1; for x = -1, y = 1-2 = -1. This will keep the same V shape but start at (0, -2).
04
Draw the Graph
With these points plotted, draw lines from the vertex (0, -2) rising rightwards through (1, -1) and leftwards through (-1, -1). These two lines will continue as y = x - 2 for x ≥ 0, and y = -x - 2 for x < 0.
05
Verify
Finally, make sure the graph maintains its V shape and labels the vertex at (0, -2). Check the key points to ensure accuracy, from both the left and right arms of the V intersecting properly through these points.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Transformations of Functions
Transformations of functions are crucial for adapting a basic graph into a different shape or position on the coordinate plane. Types of transformations include:
- Vertical shifts: Moving the graph up or down parallel to the y-axis.
- Horizontal shifts: Moving the graph left or right parallel to the x-axis.
- Reflections: Flipping the graph over a particular axis.
- Stretching or compressing: Changing the graph's shape by stretching or compressing it along the x or y-axis.
V-shaped Graphs
V-shaped graphs are characteristic of absolute value functions like \( y = |x| \). The "V" is formed because absolute value functions reflect both positive and negative entries into positive outputs.
- Vertex: The point at the tip of the V, serving as a pivot point. For \( y = |x| \), this vertex is at the origin (0, 0).
- Arms of the V: These are linear components that extend from the vertex. One arm represents \( y = x \) and the other \( y = -x \), both extending indefinitely.
Graphing Techniques
Graphing techniques help visualize functions reliably and accurately. Begin with plotting key points to provide a framework for your graph:
- Identify the vertex: Start with the vertex; for the transformed graph \( y = |x| - 2 \), this is at (0, -2).
- Plot additional points: Use simple values, like \( x = 1 \) or \( x = -1 \), to determine additional coordinates such as (1, -1) and (-1, -1).
- Connect the points: Draw lines that connect these coordinates, extending the arms of the V.
Algebraic Functions
Algebraic functions, like absolute value functions, combine constants, variables, and operations. The function \( y = |x| - 2 \) uses the absolute value operation, which alters how regular functions behave.
- Absolute value operation: Converts all negative inputs to positive, resulting in the distinctive V-shape.
- Linear components: Each arm of the V graphed corresponds to linear equations like \( y = x - 2 \) for \( x \geq 0 \) and \( y = -x - 2 \) for \( x < 0 \).
- Variable manipulation: By shifting the function down, we alter the constant term, highlighting these graphing transformations.