Chapter 9: Problem 48
Find the inverse of \(f(x)=3 x-4\).
Short Answer
Expert verified
The inverse of the function \(f(x)=3x-4\) is \(f^{-1}(x)=(x+4)/3\)
Step by step solution
01
Replace \(f(x)\) with \(y\)
To make the operations easier, replace \(f(x)\) with \(y\). So, instead of \(f(x)=3x-4\), the function becomes \(y=3x-4\)
02
Swap \(x\) and \(y\)
Now, swap the places of \(x\) and \(y\). The equation then becomes \(x=3y-4\)
03
Solve for \(y\)
To find the inverse function, solve this equation for \(y\). First, isolate the term with \(y\) by adding 4 to both sides. This results in the equation \(x+4=3y\). Next, divide both sides by 3 to solve for \(y\). The final inverse function is \(y=(x+4)/3\)
04
Replace \(y\) with \(f^{-1}(x)\)
Now that you have solved for \(y\), replace it with \(f^{-1}(x)\). Therefore, the inverse function is \(f^{-1}(x)=(x+4)/3\).
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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 compact and convenient way to represent functions in mathematics. It helps us identify and work with functions more easily by using symbols like \( f(x) \). In the context of a function, \( f \) is the name of the function, and \( x \) is the variable or input. For example, \( f(x) = 3x - 4 \) means that \( f \) outputs a value that is 3 times the input \( x \), minus 4.
- When you see \( f(x) \), remember it's just a name, not a multiplication of \( f \) and \( x \).
- Function notation allows us to evaluate a function by replacing \( x \) with a specific number. For example, \( f(2) \) would mean substituting 2 into the function, so \( f(2) = 3(2) - 4 \).
Solving Equations
Solving equations is about finding the value of a variable that makes the equation true. When finding the inverse of a function, equation solving is key, because you interchange and solve for the dependent variable to find its inverse.To solve the equation \( y = 3x - 4 \) for its inverse:
- We start by swapping \( x \) and \( y \). This means setting \( x = 3y - 4 \), which means that what was the output is now the input.
- Next, we isolate \( y \) by reversing the operations done to \( x \). To do this, first add 4 to both sides, giving us \( x + 4 = 3y \).
- Then, divide both sides by 3 to solve for \( y \), resulting in \( y = \frac{x + 4}{3} \), thus yielding the inverse function.
Algebraic Manipulation
Algebraic manipulation refers to the process of re-arranging and simplifying equations to find solutions. It involves performing operations like addition, subtraction, multiplication, and division to transform equations into a more workable form.Here’s how algebraic manipulation was used in finding the inverse of the function \( y = 3x - 4 \):
- Once you swap \( x \) and \( y \) as in \( x = 3y - 4 \), the first step is to add 4 to both sides to undo the subtraction of 4. This manipulation results in \( x + 4 = 3y \).
- The next manipulation involves dividing both sides by 3 to solve for \( y \). This step transforms the equation into \( y = \frac{x + 4}{3} \).