Chapter 5: Problem 21
For the following exercises, find the inverse of the functions. $$ f(x)=3-\sqrt[3]{x} $$
Short Answer
Expert verified
The inverse is \( f^{-1}(x) = (3-x)^3 \).
Step by step solution
01
Replace the Function Notation
First, replace the function notation \( f(x) \) with \( y \) to make the equation easier to work with. The equation becomes \( y = 3 - \sqrt[3]{x} \).
02
Swap the Variables
Exchange the positions of \( x \) and \( y \). The equation now becomes \( x = 3 - \sqrt[3]{y} \). This will help us find the inverse of the function.
03
Isolate the Radical
Rearrange the equation to solve for \( \sqrt[3]{y} \). Subtract 3 from both sides to get \( \sqrt[3]{y} = 3 - x \).
04
Solve for the New Variable
To isolate \( y \), cube both sides of the equation to eliminate the cube root. This results in \( y = (3 - x)^3 \).
05
Write the Inverse Function
Replace \( y \) with \( f^{-1}(x) \) to express the inverse function. Therefore, the inverse function is \( f^{-1}(x) = (3 - x)^3 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Notation
Function notation is a way to symbolize equations with a function format, usually denoted by letters like \( f \) or \( g \). It allows us to specify that one variable depends on another. A common form is \( f(x) \), where \( f \) symbolizes a function and \( x \) is the input value. When evaluating the function, you replace \( x \) with a specific number to find the output. If the function is \( f(x) = 3 - \sqrt[3]{x} \), you can substitute any number for \( x \) to find its corresponding output. This notation helps make complex ideas more understandable and manageable.Some important points about function notation:
- It clearly indicates which variable is independent (usually \( x \)) and dependent (often \( f(x) \)).
- It makes complex expressions easier to interpret and manipulate.
- Function notation is especially useful when performing operations like finding inverse functions.
Cubed Root
The cubed root function is the inverse operation of cubing a number. In simpler terms, whereas cubing a number means multiplying it by itself three times, finding the cubed root involves determining what number, when cubed, gives the original number. It is represented by the symbol \( \sqrt[3]{x} \). For example, \( \sqrt[3]{8} = 2 \) because \( 2^3 = 8 \). Finding cube roots is a crucial skill in solving equations involving cubic terms.Here are some things to keep in mind about cubed roots:
- The cubed root of a negative number is negative, as it maintains its sign. For instance, \( \sqrt[3]{-8} = -2 \).
- Cubed roots, unlike square roots, apply to all real numbers without restrictions.
- They are often used when isolating variables in equations, especially in inverse functions.
- Understanding cubed roots helps in simplifying expressions and solving cubic equations.
Inverse Function Finding
Finding the inverse of a function is like solving a puzzle. It involves reversing the roles of the input and output to determine the original input from a given output. This is a vital process in algebra because it helps us understand how different values relate within a function. To find an inverse function, follow these general steps:
- Start by replacing the function notation \( f(x) \) with \( y \).
- Swap the dependent variable \( y \) with the independent variable \( x \), which rearranges the equation.
- Solve the new equation to express \( y \) in terms of \( x \).
- Rewrite the solved form by replacing \( y \) with \( f^{-1}(x) \), representing the inverse function.
Variable Swapping
One of the interesting concepts in algebra is variable swapping, which is a crucial step when finding inverse functions. This technique involves switching the places of the variables in an equation. For example, you might start with \( y = 3 - \sqrt[3]{x} \) and swap \( x \) and \( y \), resulting in \( x = 3 - \sqrt[3]{y} \). This swap is the first step in rearranging the equation to solve for the inverse.Here’s how swapping helps in mathematics:
- It transforms the equation, so the dependent variable becomes independent, and vice versa.
- Enable users to solve equations more intuitively by focusing on reversing the function's operation.
- It's important because without swapping, isolating the function terms to reflect the inverse becomes complicated.