Chapter 5: Problem 21
\(f(x)=\sqrt[3]{x}, g(x)=-\sqrt[3]{x}-1\)
Short Answer
Expert verified
Function \(f(x)\) is the cube root of any input \(x\). Function \(g(x)\) is the same function but with each output negated (hence a reflection) and then subtracted by 1 (a downward movement of the function)
Step by step solution
01
Analyze the function \(f(x)\)
The function \(f(x) = \sqrt[3]{x}\) is a basic cube root function which denotes that each input \(x\) will be evaluated by finding its cube root.
02
Analyze the function \(g(x)\)
The function \(g(x) = -\sqrt[3]{x} - 1\) involves two transformations on the basic cube root function: reflection and translation. The negative in front of the cube root indicates that the function is reflected about the x-axis, while the -1 at the end denotes downward translation of the function by 1 unit.
03
Plot The Functions
While this is not a requirement of this exercice, plotting the functions would provide a visual understanding of the transformations that occur from function \(f(x)\) to function \(g(x)\). One will appear as a diagonal straight line from lower left to top right (each point on it being \(x, x^{1/3}\)). The other is exactly the same, but flipped downwards and moved one step down. This presents an easier understanding of how each of these functions would behave.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Transformations
A function transformation involves modifying a basic function to achieve a desired form or positioning. In the case of the cube root function, transformations allow us to change its shape and position on a graph. These transformations can include reflections, translations (shifting), stretching, and compressing.
For example, consider the cube root function defined as \(f(x) = \sqrt[3]{x}\), which is a core function with a distinct "s" shaped curve crossing the origin.
For example, consider the cube root function defined as \(f(x) = \sqrt[3]{x}\), which is a core function with a distinct "s" shaped curve crossing the origin.
- **Basic Transformations**: Reflections and translations change how the graph is oriented and positioned.
- **Complex Transformations**: Stretching (scaling) and compressing alter the steepness or width of the graph.
Reflection about the x-axis
Reflection of a function over the x-axis inverts the graph vertically. When a function is reflected in this manner, each point of the original function \((x, y)\) becomes \((x, -y)\). This keeps the x-values constant, but reverses the direction of the y-values.
For the function in our original exercise, \(g(x) = -\sqrt[3]{x}\), the negative sign in front of the cube root indicates this reflection. So, \(f(x) = \sqrt[3]{x}\) becomes \(g(x) = -\sqrt[3]{x}\), flipping the graph across the x-axis.
For the function in our original exercise, \(g(x) = -\sqrt[3]{x}\), the negative sign in front of the cube root indicates this reflection. So, \(f(x) = \sqrt[3]{x}\) becomes \(g(x) = -\sqrt[3]{x}\), flipping the graph across the x-axis.
- This changes all positive y-values in \(f(x)\) to negative values in \(g(x)\).
- The graph now appears to be upside down when compared to the original.
Downward Translation
Translation of a function involves shifting the entire graph without altering its shape. It can be performed vertically or horizontally. A downward translation moves the graph lower along the y-axis by a set number of units.
For the function \(g(x) = -\sqrt[3]{x} - 1\), the term "-1" indicates that the entire graph is shifted one unit downward. This means every point on \(f(x)\) is moved directly down without any horizontal shift.
For the function \(g(x) = -\sqrt[3]{x} - 1\), the term "-1" indicates that the entire graph is shifted one unit downward. This means every point on \(f(x)\) is moved directly down without any horizontal shift.
- Every point \((x, y)\) now aligns at \((x, y - 1)\).
- This shifts the transformation from the reflection further down the y-axis.
Plotting Functions
Plotting functions provides visual clarity on how transformations affect a function graphically. Starting with a basic function like \(f(x) = \sqrt[3]{x}\), each transformation we apply changes its appearance on the Cartesian plane.
To plot the original and transformed functions:
To plot the original and transformed functions:
- Plot \(f(x) = \sqrt[3]{x}\) where the curve passes through the origin and demonstrates the increasing cube root values.
- Then add the transformation actions. Reflect \(-\sqrt[3]{x}\) becomes the inverted graph.
- Finally, apply the translation by moving the curve of \(g(x) = -\sqrt[3]{x} - 1\) one unit down.