Chapter 5: Problem 32
Explain how the graph of \(f\) can be obtained from the graph of \(y=\frac{1}{x}\) or \(y=\frac{1}{x^{2}} .\) Draw a sketch of the graph of \(f\) by hand. Then generate an accurate depiction of the graph with a graphing calculator. Finally, give the domain and range. $$f(x)=\frac{-1}{(x-4)^{2}}+2$$
Short Answer
Expert verified
Shift right 4, reflect x-axis, shift up 2; Domain: \(x \neq 4\); Range: \((-\infty, 2)\).
Step by step solution
01
Identify Base Graph
The given function is a transformation of the base graph \(y = \frac{1}{x^2}\). This is an important note, as it will help guide the transformations we apply.
02
Apply Horizontal Shift
The function \(f(x) = \frac{-1}{(x-4)^{2}} + 2\) includes a horizontal shift component: \(x - 4\). This means that the graph of \(y = \frac{1}{x^2}\) is shifted 4 units to the right.
03
Apply Vertical Stretch/Shrink and Reflection
The coefficient of \(-1\) in \(\frac{-1}{(x-4)^2}\) indicates two transformations: the graph reflects across the x-axis and there is a vertical stretch. This changes the graph, flipping it upside down.
04
Apply Vertical Shift
The constant \(+2\) at the end of the function indicates the vertical shift upwards by 2 units. This moves the entire graph up by 2 units along the y-axis.
05
Sketch the Graph
Combine all transformations. Start from \(y = \frac{1}{x^2}\), shift right by 4, reflect across the x-axis, and move up by 2 units. Sketch this on graph paper.
06
Domain and Range
The domain of \(f(x) = \frac{-1}{(x-4)^{2}} + 2\) is all real numbers except \(x = 4\), because \((x-4)^2\) cannot be zero. The range of this function is \((-\infty, 2)\), because the graph has a horizontal asymptote at \(y = 2\), and the graph never actually reaches 2.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Horizontal Shift
When examining the function \(f(x) = \frac{-1}{(x-4)^{2}} + 2\), one of the key transformations is the horizontal shift. A horizontal shift moves the graph left or right along the x-axis.
- The component \(x-4\) in the denominator denotes this horizontal shift.
- Specifically, it tells us that the graph of the base function \(y = \frac{1}{x^2}\) is shifted 4 units to the right.
Vertical Stretch
Another transformation present in \(f(x) = \frac{-1}{(x-4)^{2}} + 2\) is the vertical stretch. A vertical stretch occurs when all the y-coordinates of a graph are multiplied by a factor, making the graph appear taller or shrunk.
- The multiplier \(-1\) outside the fraction performs this stretch, but it also affects graph directionality.
- Though the stretch is present, the primary outcome of \(-1\) is reflecting the graph over the x-axis, which we will dig into shortly.
Reflection
In the equation \(f(x) = \frac{-1}{(x-4)^{2}} + 2\), the reflection component arises from the \(-1\) in front of the fraction. This coefficient executes a reflection across the x-axis.
- Reflection transforms the graph upside down.
- Every y-coordinate value of the graph \(y = \frac{1}{x^2}\) is converted from positive to negative, effectively flipping it below the x-axis.
Vertical Shift
The final key transformation in the function \(f(x) = \frac{-1}{(x-4)^{2}} + 2\) involves a vertical shift. A vertical shift moves the entire graph up or down along the y-axis.
- The constant \(+2\) at the end of the function suggests a shift 2 units upwards.
- It lifts every point on the graph up by 2 units, repositioning the asymptotic behavior to reflect above the x-axis.