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Ch. 2 - Functions and Graphs
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Not the one you use?Change textbook
Chapter 3, Problem 25

The functions in Exercises 11-28 are all one-to-one. For each function, a. Find an equation for f-1(x), the inverse function. b. Verify that your equation is correct by showing that f(ƒ-1 (x)) = = x and ƒ-1 (f(x)) = x. f(x) = (x +4)/(x-2)

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1
Start by writing the function as an equation with y: \(y = \frac{x + 4}{x - 2}\).
To find the inverse, swap x and y: \(x = \frac{y + 4}{y - 2}\).
Solve this new equation for y. Begin by multiplying both sides by \((y - 2)\) to eliminate the denominator: \(x(y - 2) = y + 4\).
Distribute x on the left side: \(xy - 2x = y + 4\). Then, collect all terms involving y on one side and constants on the other: \(xy - y = 2x + 4\).
Factor y out on the left: \(y(x - 1) = 2x + 4\). Finally, solve for y by dividing both sides by \((x - 1)\): \(y = \frac{2x + 4}{x - 1}\). This expression represents \(f^{-1}(x)\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

One-to-One Functions

A function is one-to-one if each output corresponds to exactly one input, ensuring it has an inverse. This property is crucial because only one-to-one functions have well-defined inverse functions that reverse the original mapping.
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Finding the Inverse Function

To find the inverse of a function, swap the roles of x and y in the equation and solve for y. This process reverses the input-output relationship, producing a function that undoes the effect of the original function.
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Verification of Inverse Functions

To verify an inverse function, show that composing the function and its inverse in both orders returns the original input: f(f⁻¹(x)) = x and f⁻¹(f(x)) = x. This confirms the two functions are true inverses of each other.
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