Chapter 1: Problem 30
\(23-36=\) Graph the function by hand, not by plotting points, but by starting with the graph of one of the standard functions and then applying the appropriate transformations. $$y=\frac{2}{x}-2$$
Short Answer
Expert verified
Vertical stretch by 2 and shift down by 2 units applied to \( y = \frac{1}{x} \).
Step by step solution
01
Identify the Standard Function
The function we are working with is \( y = \frac{2}{x} - 2 \). The standard function that forms the basis of our transformation is \( y = \frac{1}{x} \). This function is a rational function known for its hyperbolic shape, with vertical asymptote at \( x=0 \) and horizontal asymptote at \( y=0 \).
02
Apply Vertical Stretch
The given function \( y = \frac{2}{x} \) can be seen as a vertical stretch of the standard function \( y = \frac{1}{x} \). The factor \( 2 \) in the numerator stretches the graph vertically by a factor of 2. This means the values of \( y \) become twice as large for each \( x \) compared to the standard function \( y = \frac{1}{x} \).
03
Apply Vertical Shift
Next, the transformation \( y = \frac{2}{x} - 2 \) from the function \( y = \frac{2}{x} \) is a vertical shift. Subtracting 2 from the whole expression shifts the entire graph downward by 2 units. Consequently, this affects the horizontal asymptote, which is now \( y = -2 \) instead of \( y = 0 \).
04
Sketch the Transformed Function
With the graph of \( y = \frac{1}{x} \) vertically stretched and shifted, we can sketch \( y = \frac{2}{x} - 2 \). The resulting graph is similar in shape to \( y = \frac{1}{x} \), but steeper due to the vertical stretch, and positioned such that its horizontal asymptote is at \( y = -2 \) and its vertical asymptote remains at \( x = 0 \). Make sure to reflect these changes in your hand-drawn graph.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vertical Stretch
A vertical stretch is a transformation that changes the vertical scale of a graph. For the function \( y = \frac{2}{x} \), the number \( 2 \) in the numerator implies that each \( y \)-value is scaled by a factor of 2 compared to the function \( y = \frac{1}{x} \). Here's how it works:
- Imagine grabbing the graph at every point and pulling it away from the horizontal axis, effectively doubling its distance.
- This does not affect the positions of the asymptotes (the lines that the graph approaches but never touches).
Vertical Shift
A vertical shift involves moving the graph up or down along the \( y \)-axis. In our function, \( y = \frac{2}{x} - 2 \), the \(-2\) indicates a downward shift of the entire graph.Here's what happens:
- Every point of the graph is moved 2 units downward. This affects the horizontal asymptote, shifting it from \( y = 0 \) to \( y = -2 \).
- The vertical stretch from the earlier step remains intact, meaning the graph stays steeper than the standard function.
Asymptotes
An asymptote is a line that a graph approaches but never actually touches. Understanding asymptotes is key to working with rational functions like \( y = \frac{2}{x} - 2 \).For this graph, we have:
- A vertical asymptote at \( x = 0 \), which remains unchanged regardless of stretching or shifting. It indicates that the graph will go towards infinity as \( x \) approaches 0 from either direction.
- A horizontal asymptote was originally at \( y = 0 \) for the standard function \( y = \frac{1}{x} \). However, due to the vertical shift, it moves to \( y = -2 \).
Transformations of Functions
Transformations involve altering a function's graph in a predictable manner. When handling rational functions like \( y = \frac{2}{x} - 2 \), the key transformations involve stretching and shifting.To transform a function's graph:
- First, identify the changes in scale, which involve stretches or compressions. In our case, this is the vertical stretch by factor 2.
- Next, check for shifts. For our function, we have a vertical shift moving the graph 2 units down.