Chapter 0: Problem 40
Use a computer or a graphing calculator in Problems \(37-40 .\) Let \(f(x)=1 /\left(x^{2}+1\right)\). Using the same axes, draw the graphs of \(y=f(x), y=f(2 x),\) and \(y=f(x-2)+0.6,\) all on the domain [-4,4]
Short Answer
Expert verified
Graph \( f(x) = \frac{1}{x^2+1} \), \( f(2x) = \frac{1}{4x^2+1} \), \( f(x-2)+0.6 = \frac{1}{(x-2)^2+1}+0.6 \) over \([-4, 4]\).
Step by step solution
01
Define the Functions
First, let's clearly define each function we need to graph. We have three functions:- The original function is \( f(x) = \frac{1}{x^2 + 1} \).- The transformed function \( y = f(2x) \) means we will evaluate the function at \( 2x \), giving us \( y = \frac{1}{(2x)^2 + 1} = \frac{1}{4x^2 + 1} \).- The function \( y = f(x-2) + 0.6 \) implies a horizontal shift to the right by 2 and a vertical shift upwards by 0.6, so \( y = \frac{1}{(x-2)^2 + 1} + 0.6 \).
02
Set Up the Graphing Range
We are instructed to graph all functions over the domain \([-4, 4]\). This means for each function, we'll evaluate and plot the function values starting at \( x = -4 \) and ending at \( x = 4 \).
03
Graph the First Function
Using your calculator or graphing software, graph \( y = \frac{1}{x^2 + 1} \). Note that this function is symmetric about the y-axis and peaks at \( x = 0 \) with a maximum value of 1. It decreases as \( |x| \) increases, approaching 0 as \( x \) approaches ±4.
04
Graph the Second Function
Now graph \( y = \frac{1}{4x^2 + 1} \). This transformation compresses the graph horizontally by a factor of 2. This means the maximum value remains the same at 1, but the function decreases more rapidly than \( y = \frac{1}{x^2 + 1} \) as \( |x| \) increases.
05
Graph the Third Function
For the final function, graph \( y = \frac{1}{(x-2)^2 + 1} + 0.6 \). This graph is shifted 2 units to the right, so it now peaks at \( x = 2 \), and the whole graph is raised by 0.6. This means the maximum value is 1.6 at \( x = 2 \).
06
Analyze the Graphs
Observe the differences in each transformation:- The compression with \( y = f(2x) \) results in a narrower graph.- The horizontal and vertical shift in \( y = f(x-2) + 0.6 \) moves the peak to \( x = 2 \) and lifts the entire curve upwards.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Horizontal Shift
A horizontal shift affects the position of the graph along the x-axis. When we look at the function transformation from \(f(x) = \frac{1}{x^2 + 1}\) to \(y = f(x-2) + 0.6\), we see a horizontal shift to the right by 2 units. This is caused by replacing \(x\) with \(x-2\) inside the function. Visually, every point on the graph moves 2 units to the right.
- The term \(x-2\) means that the graph is shifted rightward by 2 units.
- This keeps the shape of the graph the same, since the overall relationship between variables is unchanged.
- It’s crucial to remember that a negative sign in \(x-a\) results in movement to the right.
Vertical Shift
Vertical shifts change the position of the graph along the y-axis. In the function transformation \(y = f(x-2) + 0.6\), there's a vertical shift because of the "+0.6" outside the function. This means every point on the graph moves upwards by 0.6 units.
- The "+0.6" indicates an upward shift of the entire graph.
- This doesn’t change the shape or the width of the graph, only its vertical position.
- Vertical shifts are straightforward: a plus sign moves the graph up, and a minus sign would move it down.
Function Compression
Function compression refers to the squeezing or stretching of a graph along the x-axis. In the transformation from \(f(x) = \frac{1}{x^2 + 1}\) to \(y = f(2x)\), we observe horizontal compression. This happens when we perform a transformation by multiplying the \(x\) variable inside the function by a constant, in this case, 2.
- The transformation \(f(2x)\) means that each x-value is halved, causing the graph to compress.
- This results in a steeper graph that reaches its peak more quickly and declines faster than the original.
- Horizontal compression or stretching affects how ‘wide’ or ‘narrow’ the graph appears.