Chapter 12: Problem 40
Each function is one-to-one. Find its inverse. $$ f(x)=\frac{-3 x+2}{3 x-4}, \quad x \neq \frac{4}{3} $$
Short Answer
Expert verified
The inverse function is \( f^{-1}(x) = \frac{2 + 4x}{3x + 3} \).
Step by step solution
01
Write the function equation
Start with the given function equation: \[ f(x) = \frac{-3x + 2}{3x - 4} \]
02
Replace f(x) with y
Substitute \( y \) for \( f(x) \): \[ y = \frac{-3x + 2}{3x - 4} \]
03
Swap x and y
Interchange \( x \) and \( y \): \[ x = \frac{-3y + 2}{3y - 4} \]
04
Solve for y
Multiply both sides by \( 3y - 4 \) to eliminate the fraction: \[ x(3y - 4) = -3y + 2 \]
05
Distribute x
Distribute \( x \) on the left side: \[ 3xy - 4x = -3y + 2 \]
06
Collect y terms on one side
Move all terms involving \( y \) to one side and the remaining terms to the other: \[ 3xy + 3y = 2 + 4x \]
07
Factor out y
Factor \( y \) out on the left side: \[ y(3x + 3) = 2 + 4x \]
08
Solve for y
Isolate \( y \) by dividing both sides by \( 3x + 3 \): \[ y = \frac{2 + 4x}{3x + 3} \]
09
Write the inverse function
The inverse function is: \[ f^{-1}(x) = \frac{2 + 4x}{3x + 3} \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
One-to-One Functions
Understanding one-to-one functions is crucial in finding inverses. A function is one-to-one if every output value is paired with a unique input value. This means that if \(f(a) = f(b)\), then \(a = b\). To check if a function is one-to-one, you can use the horizontal line test: if any horizontal line intersects the graphed function at most once, the function is one-to-one.
Solving Equations
To find the inverse of a function, you need to solve for the variable. Starting from the given function \(f(x) = \frac{-3x + 2}{3x - 4}\), substitute \(f(x)\) with \y \, resulting in \(y = \frac{-3x + 2}{3x - 4}\). Interchanging \(x \) and \(y \), gives \(x = \frac{-3y + 2}{3y - 4}\). From here, you need to isolate \ y\. Multiply both sides by \(3y - 4\) to clear the fraction: \[ x(3y - 4) = -3y + 2 \] Distribute \(x \) and rearrange the terms to: \[3xy - 4x = -3y + 2\] Move the \( y\) terms to one side: \[3xy + 3y = 2 + 4x\] Factor out \(y \) to get: \[y(3x + 3) = 2 + 4x\] Finally, solve for \ y\: \[y = \frac{2 + 4x}{3x + 3}\] Thus, the inverse function is \(f^{-1}(x) = \frac{2 + 4x}{3x + 3}\).
Function Inverses
Finding the inverse of a function involves reversing the roles of inputs and outputs. For the function \(f(x) = \frac{-3x + 2}{3x - 4}\), to find its inverse follow these steps:
- Step 1: Write \(f(x)\) as \(y = \frac{-3x + 2}{3x - 4}\).
- Step 2: Swap \(x \) and \(y \) to get \ x = \frac{-3y + 2}{3y - 4} \.
- Step 3: Solve for \( y\).