Chapter 0: Problem 21
Sketch the graph of the equation by translating, reflecting, compressing, and stretching the graph of \(y=x^{2}, y=\sqrt{x}\), \(y=1 / x, y=|x|\), or \(y=\sqrt[3]{x}\) appropriately. Then use a graphing utility to confirm that your sketch is correct. $$ y=1-2 \sqrt[3]{x} $$
Short Answer
Expert verified
Reflect and stretch \(y = \sqrt[3]{x}\) by 2, translate up by 1.
Step by step solution
01
Identify the Base Function
The given equation is \( y = 1 - 2 \sqrt[3]{x} \). The base function here is \( y = \sqrt[3]{x} \), which is the cube root function.
02
Identify Transformations
The equation \( y = 1 - 2 \sqrt[3]{x} \) includes several transformations of the base function \( y = \sqrt[3]{x} \):1. \(-2\) means there is a vertical stretch by a factor of 2 and a reflection across the x-axis.2. \(+1\) means a vertical translation upwards by 1 unit.
03
Perform Reflection and Stretch
Reflect the graph of \( y = \sqrt[3]{x} \) over the x-axis and then stretch it vertically by a factor of 2 to get \( y = -2\sqrt[3]{x} \). The cube root function is a symmetry about the origin, so the reflection involves simply flipping it over the x-axis.
04
Apply Vertical Translation
Translate the graph of \( y = -2\sqrt[3]{x} \) vertically upwards by 1 unit to get the final graph \( y = 1 - 2\sqrt[3]{x} \). This means every point on \( y = -2\sqrt[3]{x} \) is moved up by 1 unit.
05
Sketch the Graph
First, sketch the basic graph of \( y = \sqrt[3]{x} \). Then, apply the transformations: reflect and stretch the graph to get \( y = -2\sqrt[3]{x} \), and finally translate it up by 1 unit to sketch \( y = 1 - 2\sqrt[3]{x} \). This graph will pass through the point \((0, 1)\) and continue to show the basic cube root shape.
06
Verify using Graphing Utility
Use a graphing utility (such as Desmos or a graphing calculator) to plot the function \( y = 1 - 2\sqrt[3]{x} \) and verify that it matches your sketched graph. Check key points and the behavior of the graph to ensure accuracy.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Reflecting Functions
Reflecting a function across an axis involves flipping its graph over that axis. In the case of the equation \( y = 1 - 2\sqrt[3]{x} \), the \(-2\sqrt[3]{x}\) part indicates a reflection across the x-axis. This results in all positive y-values of the original \( y = \sqrt[3]{x} \) turning negative and vice versa.
When graphing, you start by picturing the \( y = \sqrt[3]{x} \) graph, which has a distinct 'S' shape around the origin. Reflecting it over the x-axis flips this shape upside down. So, parts of the curve above the x-axis move below, and those below move above, creating \( y = -\sqrt[3]{x} \).
- Reflecting across the x-axis: \( y = f(x) \rightarrow y = -f(x) \)
This reflection changes the sign of the y-values but keeps the x-values unchanged. Such reflections are useful to invert the behavior of the function, making a crest into a trough and so forth. Understanding this basic transformation helps simplify tackling more complex equations.
When graphing, you start by picturing the \( y = \sqrt[3]{x} \) graph, which has a distinct 'S' shape around the origin. Reflecting it over the x-axis flips this shape upside down. So, parts of the curve above the x-axis move below, and those below move above, creating \( y = -\sqrt[3]{x} \).
- Reflecting across the x-axis: \( y = f(x) \rightarrow y = -f(x) \)
This reflection changes the sign of the y-values but keeps the x-values unchanged. Such reflections are useful to invert the behavior of the function, making a crest into a trough and so forth. Understanding this basic transformation helps simplify tackling more complex equations.
Vertical Stretching
Vertical stretching scales a function's graph along the y-axis. In the function \( y = 1 - 2\sqrt[3]{x} \), the factor of 2 in \(-2\sqrt[3]{x}\) specifically stretches the graph vertically. This means each point on the function \( y = \sqrt[3]{x} \) gets pulled away from the x-axis.
To visualize this, consider how the original cube root function, \( y = \sqrt[3]{x} \), spreads its growth gradually. Vertical stretching magnifies this growth, making it more pronounced. Every y-coordinate value becomes twice as far from the x-axis as it was originally. The endpoints move farther from zero, increasing the function's steepness visibly.
- Vertical Stretch: \( y = f(x) \rightarrow y = af(x) \) where \(|a| > 1 \)
This change does not alter the x-intercepts but modifies the curve's y-coordinates, enhancing the amplitude of each point based on the stretch factor. Recognizing vertical stretching helps anticipate how a graph's steepness or spread widens in different equations.
To visualize this, consider how the original cube root function, \( y = \sqrt[3]{x} \), spreads its growth gradually. Vertical stretching magnifies this growth, making it more pronounced. Every y-coordinate value becomes twice as far from the x-axis as it was originally. The endpoints move farther from zero, increasing the function's steepness visibly.
- Vertical Stretch: \( y = f(x) \rightarrow y = af(x) \) where \(|a| > 1 \)
This change does not alter the x-intercepts but modifies the curve's y-coordinates, enhancing the amplitude of each point based on the stretch factor. Recognizing vertical stretching helps anticipate how a graph's steepness or spread widens in different equations.
Vertical Translation
Vertical translation involves shifting the graph up or down along the y-axis without altering its shape. In \( y = 1 - 2\sqrt[3]{x} \), the \(+1\) indicates that every point on \( y = -2\sqrt[3]{x} \) is moved up by 1 unit.
This can be visualized as a smooth glide of the function in a parallel manner, which means the shape of the function remains unchanged, but its position shifts vertically. In practical terms, adding 1 to the equation results in all y-values getting increased by 1, thus relocating the curve upwards on the graph.
- Vertical Translation: \( y = f(x) + c \)
Vertical translations are instrumental in adjusting the starting point or baseline of a function without affecting its structure. By mastering this concept, you can re-position any graph to the desired interval on the y-axis, easily adapting the graphs to specific context or constraints in your problems.
This can be visualized as a smooth glide of the function in a parallel manner, which means the shape of the function remains unchanged, but its position shifts vertically. In practical terms, adding 1 to the equation results in all y-values getting increased by 1, thus relocating the curve upwards on the graph.
- Vertical Translation: \( y = f(x) + c \)
Vertical translations are instrumental in adjusting the starting point or baseline of a function without affecting its structure. By mastering this concept, you can re-position any graph to the desired interval on the y-axis, easily adapting the graphs to specific context or constraints in your problems.