Chapter 3: Problem 16
Use algebra to find the inverse of the given one-to-one function. $$f(x)=5+\sqrt{3 x-2}$$
Short Answer
Expert verified
Answer: The inverse function is $$f^{-1}(x)=\frac{1}{3}(x^2-10x+27)$$
Step by step solution
01
Replace f(x) with y
We replace the given function $$f(x)$$ with $$y$$:
$$y=5+\sqrt{3x-2}$$
02
Swap x and y
Now, we swap $$x$$ and $$y$$ in the equation:
$$x=5+\sqrt{3y-2}$$
03
Solve for y
We will solve the equation for $$y$$ by first isolating the square root term:
Subtract 5 from both sides of the equation:
$$x-5=\sqrt{3y-2}$$
Now, square both sides to get rid of the square root:
$$(x-5)^2=(\sqrt{3y-2})^2$$
This simplifies to:
$$x^2-10x+25=3y-2$$
Now, isolate $$y$$ by adding $$2$$ and then dividing by $$3$$:
$$3y=x^2-10x+27$$
$$y=\frac{1}{3}(x^2-10x+27)$$
04
Write the inverse function
Finally, we write the inverse function using the notation $$f^{-1}(x)$$:
$$f^{-1}(x)=\frac{1}{3}(x^2-10x+27)$$
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Algebra
Algebra is like a toolbox for solving equations and manipulating expressions. It allows us to work with variables and constants to uncover values that make equations true. For example, when finding the inverse of a function, we utilize algebra to rearrange the equation to isolate the desired variable.
- We replace function notation like \( f(x) \) with a simple \( y \) to make manipulations easier.
- Next, we switch the places of \( x \) and \( y \), essentially reversing the roles. This helps us focus on finding the inverse.
- Then, using algebraic techniques such as addition, subtraction, squaring, or factoring, we solve for \( y \).
- Finally, we express \( y \) back in terms of \( x \), resulting in the inverse function.
One-to-One Functions
A one-to-one function is special because it has a unique output for every unique input. This characteristic is crucial for finding inverse functions. If a function is not one-to-one, it can’t have a proper inverse.
- Think of it as a magical machine where no two different things become the same result. In mathematics, this means that if \( f(a) = f(b) \), then \( a \) must equal \( b \).
- This uniqueness allows us to flip the function around and find its inverse, which essentially "undoes" the original function.
- For example, if you pass a number through a one-to-one function and then through its inverse, you’ll end up right where you started.
Function Notation
Function notation is a way of representing functions to easily identify inputs and outputs. It uses symbols like \( f(x) \) to indicate a function named \( f \) with input \( x \). This notation provides clarity when writing and solving problems.
- The symbol \( f \) is the name of the function, while \( x \) stands for the variable input or argument passed into this function.
- In the context of inverse functions, when we find an inverse, we write it as \( f^{-1}(x) \). This tells us that we are looking at a function that reverses \( f \).
- Using function notation, we can neatly and efficiently express operations and transformations, which helps in simplifying complex expressions.