Chapter 4: Problem 40
Find the inverse function of \(f\). $$f(x)=-x$$
Short Answer
Expert verified
The inverse function is \(f^{-1}(x) = -x\).
Step by step solution
01
Understanding the Problem
We are given a function \(f(x) = -x\) and need to find its inverse function \(f^{-1}(x)\). Recall that the inverse function is defined such that if \(y = f(x)\), then \(x = f^{-1}(y)\). This means we need to express \(x\) in terms of \(y\).
02
Replacing f(x) with y
Start by rewriting the function \(f(x) = -x\) in terms of \(y\). Set \(y = -x\). This helps to distinguish between the variables when finding the inverse.
03
Solve for x in terms of y
The next step is to solve the equation \(y = -x\) for \(x\). To do this, multiply both sides by -1, giving us \(x = -y\).
04
Express the Inverse Function
From the previous step, we found that \(x = -y\). Therefore, the inverse function is expressed by swapping the variables back such that \(y = f^{-1}(x) = -x\). Thus, the inverse is \(f^{-1}(x) = -x\).
05
Verify the Result
Verify the inverse function by checking that \(f(f^{-1}(x)) = x\) and \(f^{-1}(f(x)) = x\). Both checks prove true:1. \(f(f^{-1}(x)) = f(-x) = -(-x) = x\)2. \(f^{-1}(f(x)) = f^{-1}(-x) = -(-x) = x\)Thus, our inverse function \(f^{-1}(x) = -x\) is correct.
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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 if a function is one-to-one is crucial in determining whether an inverse function exists. A function is considered one-to-one if each input maps to a unique output. This means that no two different inputs should produce the same output. In simpler terms, a horizontal line should intersect the graph of the function at most once.
- This property ensures that we can reverse the process uniquely, making the inverse function possible.
- For example, the function \(f(x) = -x\) is one-to-one because every value of \(x\) produces a different \(f(x)\).
Function Composition
Function composition involves applying one function to the results of another, forming a linkage. It provides a verification method for calculating inverse functions. If \(f\) and \(g\) are two functions, then their composition is written as \(f(g(x))\).
- When verifying inverses, we check if \(f(f^{-1}(x)) = x\) and \(f^{-1}(f(x)) = x\).
- This ensures that the functions truly undo each other.
Domain and Range
The domain of a function is the complete set of possible input values, while the range is the set of possible output values.
- Understanding these helps in determining the boundaries and applicability of the inverse function.
- The original function \(f(x) = -x\) has a domain and range of all real numbers, denoted as \(-\infty , \infty\).
Algebraic Manipulation
Algebraic manipulation involves changing the form of a mathematical expression to solve equations or simplify expressions. It is essential in finding inverse functions efficiently.
- In our exercise, we used simple algebraic steps to find the inverse of the function \(f(x) = -x\).
- This involved rewriting the function and solving for \(x\) by multiplying both sides by -1, yielding \(x = -y\).
- The final step swapped variables back, confirming the inverse \(f^{-1}(x) = -x\).