Chapter 9: Problem 60
Find the inverse of each function. Then graph the function and its inverse on one coordinate system. Show the line of symmetry on the graph. $$ f(x)=-3 x $$
Short Answer
Expert verified
The inverse function is \( f^{-1}(x) = \frac{-x}{3} \).
Step by step solution
01
Identify the Function
The given function is linear, written as \( f(x) = -3x \). To find the inverse, we first need to consider a one-to-one function that can be reversed.
02
Swap and Solve for the Inverse
For the function \( y = -3x \), swap \( x \) and \( y \) to get \( x = -3y \). Solve for \( y \) by dividing both sides by -3, which gives \( y = \frac{-x}{3} \). The inverse function is \( f^{-1}(x) = \frac{-x}{3} \).
03
Graph the Original Function
Graph the original function \( f(x) = -3x \). This is a straight line with a slope of -3, passing through the origin (0,0).
04
Graph the Inverse Function
Graph the inverse function \( f^{-1}(x) = \frac{-x}{3} \). This is also a straight line with a slope of \(-\frac{1}{3}\), passing through the origin (0,0).
05
Draw the Line of Symmetry
In the coordinate plane, draw the line of symmetry \( y = x \). This line acts as a mirror line, showing symmetry between the original function and its inverse.
06
Confirm the Inverse
Check that compositions of the original and inverse functions return the inputs: \( f(f^{-1}(x)) = x \) and \( f^{-1}(f(x)) = x \). For \( f(f^{-1}(x)) \), substitute the inverse function into the original: \(-3(\frac{-x}{3}) = x\). Do the same reverse: substituting the original function into the inverse gives \(\frac{-(-3x)}{3} = x\). Both give \( x \), confirming correct inversion.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Linear Functions
Linear functions are a type of function that creates a straight line when graphed. They are in the form of \( f(x) = mx + b \), where \( m \) is the slope and \( b \) is the y-intercept. These simple expressions can model many real-world phenomena, like constant speed or uniform rates. The simplicity of a linear equation allows us to easily find the inverse.
- Slope (\( m \)): This number in the equation describes how steep the line is. In our example, the original function \( f(x) = -3x \) has a slope of -3, indicating the line steeply descends as it moves to the right.
- Y-intercept (\( b \)): The y-intercept is where the line crosses the y-axis. Here, the original function doesn't have a y-intercept (b=0) since it goes through the origin.
Graphing Functions
When graphing linear functions and their inverses, we illustrate how these equations translate into visual lines on a coordinate plane. This makes understanding interactions between functions clearer, especially when combined with graph features like slope and intercepts.
- Original Function: For our example, \( f(x) = -3x \), you start from the origin and plot a line descending sharply, due to the slope of -3.
- Inverse Function: The inverse, \( f^{-1}(x) = \frac{-x}{3} \), depicts a line sloping less steeply in the opposite direction, with a slope of \(-\frac{1}{3}\).
Line of Symmetry
The line of symmetry for a function and its inverse is pivotal in understanding their geometric relationship. This line, \( y = x \), serves as a reflection point where the original function reflects toward its inverse.
- Symmetry: This line shows that every point on \( f(x) \) is mirrored onto \( f^{-1}(x) \), and vice versa around this line.