Chapter 6: Problem 60
Graph both functions in the same viewing window and describe how \(g\) is a transformation of $f . $$f(x)=x^{3}, g(x)=-x^{3}$$
Short Answer
Expert verified
The function \(g(x)=-x^3\) is a reflection of \(f(x)=x^3\) across the x-axis.
Step by step solution
01
Understand the Functions
Identify the given functions: the original function is \( f(x) = x^3 \) and the transformed function is \( g(x) = -x^3 \).
02
Analyze the Parent Function
Graph the parent function \( f(x) = x^3 \). This is a cubic function that passes through the origin (0,0). The graph is symmetric about the origin and it increases from left to right.
03
Analyze the Transformation
Note that \( g(x) = -x^3 \) introduces a reflection. Specifically, it reflects the parent function \( f(x) = x^3 \) across the x-axis.
04
Graph the Transformed Function
Graph \( g(x) = -x^3 \) in the same window as \( f(x) = x^3 \). This graph will also pass through the origin (0,0) but will reflect downward through other points compared to \( f(x) = x^3 \).
05
Compare the Functions
Describe how the transformation occurred: \( g(x) \) is the reflection of \( f(x) \) over the x-axis. Every value of \( f(x) \) is multiplied by -1 to form \( g(x) \). Since \( f(x) \) produces positive output values for positive input values, \( g(x) \) produces negative output values for the same input values.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cubic Function
A cubic function is a type of polynomial function of degree three. Its general form is given by \( f(x) = ax^3 + bx^2 + cx + d \). In the given exercise, the function is \( f(x) = x^3 \), which is a simple cubic function where the coefficients b, c, and d are all zero. This results in a graph that passes through the origin (0,0).
The graph of a cubic function has a few key characteristics:
The graph of a cubic function has a few key characteristics:
- It is symmetric about the origin.
- It can pass through the origin as it does in the case of our specific function \( f(x) = x^3 \).
- As \( x \) approaches positive or negative infinity, the output values of \( f(x) \) also approach positive or negative infinity, respectively.
Reflection over the x-axis
Reflection over the x-axis is a type of transformation applied to functions. When we reflect a function over the x-axis, we multiply its output by -1. Therefore, if \( f(x) \) is the original function, its reflection over the x-axis is given by \( g(x) = -f(x) \).
In our exercise, the original function is \( f(x) = x^3 \), and its reflected function is \( g(x) = -x^3 \).
This reflection means that for every \( x \)-value in the domain:
In our exercise, the original function is \( f(x) = x^3 \), and its reflected function is \( g(x) = -x^3 \).
This reflection means that for every \( x \)-value in the domain:
- If \( f(x) \) produces a positive output, then \( g(x) \) will produce a corresponding negative output.
- Conversely, if \( f(x) \) produces a negative output, then \( g(x) \) will produce a positive output.
Graphing Functions
Graphing functions involves plotting the points that satisfy the function's equation on a coordinate plane.
When graphing \( f(x) = x^3 \), we observe certain key points:
When graphing \( g(x) = -x^3 \), we plot similar points but apply the reflection transformation:
Graphing both functions on the same coordinate plane allows us to clearly see the reflection transformation across the x-axis.
When graphing \( f(x) = x^3 \), we observe certain key points:
- At \( x = 0 \), \( f(x) = 0^3 = 0 \) (origin).
- At \( x = 1 \, f(x) = 1^3 = 1 \).
- At \( x = -1, f(x) = (-1)^3 = -1 \).
When graphing \( g(x) = -x^3 \), we plot similar points but apply the reflection transformation:
- At \( x = 0 \), \( g(x) = -(0^3) = 0 \) (origin).
- At \( x = 1, g(x) = -(1^3) = -1 \).
- At \( x = -1, g(x) = -(-1^3) = 1 \).
Graphing both functions on the same coordinate plane allows us to clearly see the reflection transformation across the x-axis.