Chapter 1: Problem 14
For each function below, find \(f^{-1}(x)\). $$ f(x)=x+5 $$
Short Answer
Expert verified
The inverse function is \(f^{-1}(x) = x - 5\).
Step by step solution
01
Understand the Problem
We need to find the inverse function \(f^{-1}(x)\) for the given function \(f(x) = x + 5\). The inverse function essentially undoes what the original function does.
02
Set Up the Equation
To find the inverse, start by writing the equation \(f(x) = y = x + 5\). In terms of inverse functions, we swap \(x\) and \(y\) and solve for the new \(x\). Thus, rewrite the equation as \(x = y + 5\).
03
Solve for the Inverse Function
Now, solve the equation \(x = y + 5\) for \(y\) to find the inverse function. Subtract 5 from both sides to get \(y = x - 5\). Therefore, the inverse function is \(f^{-1}(x) = x - 5\).
04
Verify the Inverse Function
Check if the composition of \(f(x)\) and \(f^{-1}(x)\) yields the identity function. Compute \(f(f^{-1}(x)) = f(x - 5) = (x - 5) + 5 = x\) and verify \(f^{-1}(f(x)) = f^{-1}(x + 5) = (x + 5) - 5 = x\). Both check to the identity function \(x\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Functions
A function is a special kind of relation between two sets. Specifically, it's a rule that assigns each element from a set, known as the domain, to exactly one element in another set, known as the range. Basic characteristics of functions:
- A function has a specific input (domain) and output (range).
- Every input must have a single output.
- The notation \(f(x)\) is often used to represent a function.
Equations
Equations are foundational in mathematics; they assert that two expressions are equal, often used to find unknown values. In dealing with functions and their inverses, equations help us by establishing relationships:
- In our example, to find the inverse function, we begin with the equation \(y = x + 5\).
- By swapping \(x\) and \(y\), the equation becomes \(x = y + 5\).
- We then solve for \(y\) by subtracting 5 from both sides, arriving at \(y = x - 5\).
Identity Function
The identity function is a special type of function that maps every element to itself. In simple terms, an identity function is expressed as \(f(x) = x\).When we find an inverse, we're interested in checking if applying a function and then its inverse brings us back to our original starting point, which is essentially what the identity function represents.
- When we compose a function \(f(x)\) with its inverse \(f^{-1}(x)\), the result should be the identity function.
- In our exercise, we verified this by demonstrating that \(f(f^{-1}(x)) = x\) and \(f^{-1}(f(x)) = x\).