Chapter 1: Problem 54
Write a formula for the function that results when the given toolkit function is transformed as described. \(f(x)=\frac{1}{x}\) vertically stretched by a factor of \(8,\) then shifted to the right 4 units and up 2 units.
Short Answer
Expert verified
The function is \( f(x) = \frac{8}{x-4} + 2 \).
Step by step solution
01
Identify the base function
The given function is a reciprocal function, which is expressed as \( f(x) = \frac{1}{x} \). Our task is to apply certain transformations to this function.
02
Apply the vertical stretch
To vertically stretch the function by a factor of 8, we multiply the entire function by 8. So the transformed function becomes \( 8 \cdot f(x) = 8 \cdot \frac{1}{x} = \frac{8}{x} \).
03
Shift the graph to the right
To shift the function 4 units to the right, we replace \( x \) with \( x-4 \). Therefore, the function becomes \( \frac{8}{x-4} \).
04
Shift the graph upwards
To shift the function up 2 units, we add 2 to the entire function. The final transformed function is \( f(x) = \frac{8}{x-4} + 2 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Reciprocal Function
A reciprocal function is a type of rational function usually expressed in the form \( f(x) = \frac{1}{x} \). It is called "reciprocal" because it involves taking the reciprocal (or the multiplicative inverse) of the variable \( x \). This function has some unique characteristics:
- It has two asymptotes, which are lines that the graph of the function approaches but never touches. For \( f(x) = \frac{1}{x} \), these are the x-axis (horizontal asymptote) and y-axis (vertical asymptote).
- It will not cross the axes, as the value of \( f(x) \) becomes infinite as \( x \) approaches zero.
- The graph of \( f(x) = \frac{1}{x} \) will be symmetrical along the line \( y = x \), forming a hyperbola.
Vertical Stretch
A vertical stretch changes the steepness or height of a graph without altering its horizontal dimensions. To achieve a vertical stretch of a function \( f(x) \), you multiply the entire function by a positive constant \( a \) where \( a > 1 \). This multiplication increases the distance of the points from the x-axis, making the graph taller.
- In the example \( f(x) = \frac{1}{x} \), a vertical stretch by a factor of 8 would transform it to \( g(x) = 8 \cdot f(x) = \frac{8}{x} \).
- This transformation means each point's distance from the x-axis has increased eightfold, making the curve steeper around the origin.
- Despite this change, the asymptotes remain unchanged, keeping their positions along the x-axis and y-axis.
Horizontal Shift
A horizontal shift moves the graph of a function left or right without altering its shape. To shift a function to the right by \( h \) units, substitute \( x \) with \( x-h \) in the function's formula. Conversely, substituting \( x \) with \( x+h \) will shift it to the left by \( h \) units.
- For \( f(x) = \frac{1}{x} \), a right shift of 4 units modifies it to \( g(x) = \frac{8}{x-4} \).
- This adjustment moves every point on the graph 4 units to the right, including its vertical asymptote, which shifts from \( x = 0 \) to \( x = 4 \).
- While the horizontal asymptote remains unchanged at \( y = 0 \), the overall placement of the graph shifts horizontally.
Vertical Shift
A vertical shift involves moving the entire graph up or down along the y-axis. To shift a function vertically, you can add or subtract a constant from the whole function.
- If you add \( k \) to \( f(x) \), the function shifts upward by \( k \) units; subtracting \( k \) shifts it downward.
- For the function \( g(x) = \frac{8}{x-4} \), adding 2 results in the new function \( h(x) = \frac{8}{x-4} + 2 \).
- This upward shift moves every point on the graph 2 units higher and raises the horizontal asymptote from \( y = 0 \) to \( y = 2 \).