Chapter 3: Problem 44
Use transformations to explain how the graph of \(f\) can be found by using the graph of \(y=x^{2}\) \(y=\sqrt{x},\) or \(y=|x| .\) You do not need to graph \(y=f(x)\). \(f(x)=|4-x |\)
Short Answer
Expert verified
The graph of \( f(x) = |4-x| \) is found by shifting the graph of \( y=|x| \) 4 units to the right.
Step by step solution
01
Identify the base function
The function given is \( f(x) = |4-x| \). Notice that it is based on the function \( y=|x| \). This is because the absolute value operation is involved, which corresponds directly to \( y = |x| \).
02
Replace \(x\) in the base function
In the base function \( y = |x| \), replace \( x \) with \( 4-x \). This reflects the transformation applied to the base function. The expression \( |4-x| \) means the graph of \( y=|x| \) has been horizontally transformed.
03
Horizontal Reflection
The transformation \( |4-x| \) can be rewritten as \( |-(x-4)| \). This indicates that first, the graph of \( y=|x| \) is reflected across the vertical axis because of the negative sign inside the absolute function, leading to \( y=|-x| \) which is identical to \( y=|x| \).
04
Translate the graph horizontally
The term \( x-4 \) signifies a horizontal shift. Since it is \( x-4 \), it shifts the graph to the right by 4 units. Thus, the graph of \( y = |x| \) is translated 4 units to the right to become \( y=|x-4| \), which retains the same absolute value V-shape but moves rightward on the x-axis.
05
Final Function Transformation
Combining the horizontal reflection and translation, the transformation to the graph for the function \( f(x) = |4-x| \) is effectively a horizontal shift of the \( y = |x| \) graph, 4 units to the right with no vertical changes. The negative sign affects the reflection, but results in the same shape as original. Therefore, the fully transformed graph is \( y = |(x-4)| \), equivalent to \( y = |4-x| \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Absolute Value Function
The absolute value function is a fascinating concept in mathematics, essentially taking a number and outputting its non-negative value. With the notation \( y = |x| \), the graph is created by essentially ignoring the negative signs of any input values. The graph of \( y = |x| \) characteristically resembles the letter 'V', centered at the origin (0,0) on the coordinate plane.
- The absolute value equation \( y = |x| \) ensures all output values are positive or zero.
- This is because an absolute value effectively measures the "distance" from zero, without considering direction.
- So, \(|-3| = 3\) and \(|3| = 3\), displaying the function's symmetry with respect to the y-axis.
Horizontal Shifts
Horizontal shifts in graphs occur when the entire graph of a function moves left or right along the x-axis.
For a function \( y = |x| \), a common horizontal shift is expressed by replacing \( x \) with \( x - c \) or \( x + c \). The value \( c \) determines the direction and magnitude of the shift.
However, this subtraction indicates that the movement on the x-axis is "back" by 4 units (to the positive side).
For a function \( y = |x| \), a common horizontal shift is expressed by replacing \( x \) with \( x - c \) or \( x + c \). The value \( c \) determines the direction and magnitude of the shift.
- If \( c \) is positive, \( y = |x - c| \) shifts the graph rightwards by \( c \) units.
- If \( c \) is negative, \( y = |x + c| \), shifts the graph leftwards by \( |c| \) units.
However, this subtraction indicates that the movement on the x-axis is "back" by 4 units (to the positive side).
Horizontal Reflections
Horizontal reflections involve flipping the graph of a function across a vertical line, usually the y-axis. This transformation switches the direction of the graph on the x-axis.
In the case of \( f(x) = |4-x| \), note that replacing \( x \) with \(-x\) doesn’t change the shape of the graph of an absolute value function, due to its inherent symmetry. However, writing it as \(|4-x|\) or \(|-(x-4)|\) indicates the initial reflection, even if it doesn’t visually alter the graph.
In the case of \( f(x) = |4-x| \), note that replacing \( x \) with \(-x\) doesn’t change the shape of the graph of an absolute value function, due to its inherent symmetry. However, writing it as \(|4-x|\) or \(|-(x-4)|\) indicates the initial reflection, even if it doesn’t visually alter the graph.
- Reflections are typically seen in equations like \( y = |-x| \).
- For absolute value graphs, this negation reflects the graph across the y-axis, but maintains the same 'V' shape.