Chapter 2: Problem 66
Find the inverse of each function and graph both \(f\) and \(f^{-1}\) on the same coordinate plane. $$f(x)=\sqrt{x-3}$$
Short Answer
Expert verified
The inverse function is \( f^{-1}(x) = x^2 + 3 \). Graph both functions for a visual representation.
Step by step solution
01
- Identify the function
The given function is \( f(x) = \sqrt{x - 3} \).
02
- Replace \( f(x) \) with \( y \)
Start by setting \( y = \sqrt{x - 3} \).
03
- Swap \( x \) and \( y \)
To find the inverse function, swap the variables \( x \) and \( y \). The equation becomes \( x = \sqrt{y - 3} \).
04
- Solve for \( y \)
Solve the equation \( x = \sqrt{y - 3} \) for \( y \). First, square both sides to get rid of the square root: \( x^2 = y - 3 \).
05
- Isolate \( y \)
Add 3 to both sides to isolate \( y \): \( y = x^2 + 3 \).
06
- Write the inverse function
Thus, the inverse function is \( f^{-1}(x) = x^2 + 3 \).
07
- Graph both functions
Graph the original function \( f(x) = \sqrt{x - 3} \) and the inverse function \( f^{-1}(x) = x^2 + 3 \) on the same coordinate plane. Remember that the graph of the inverse function is a reflection of the graph of the original function across the line \( y = x \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Finding the inverse of a function
When finding the inverse of a function, you're essentially reversing the process of the original function. The steps to find the inverse function ensure that for every input-output pair in the original function, the inverse will swap these roles.
Here are the core steps in depth:
Here are the core steps in depth:
- Start by identifying the given function. In this example, it's given as \(f(x) = \sqrt{x - 3}\).
- Replace \(f(x)\) with \(y\). So, \(y = \sqrt{x - 3}\).
- Swap the roles of \(x\) and \(y\), resulting in the equation \(x = \sqrt{y - 3}\).
- Solve this swapped equation for \(y\). To do this, square both sides to eliminate the square root: \(x^2 = y - 3\). Then, isolate \(y\) by adding 3 to both sides: \(y = x^2 + 3\).
- The equation you now have represents the inverse function. For this example, the inverse is \(f^{-1}(x) = x^2 + 3\).
Graphing functions
Graphing functions involves plotting them on a coordinate plane to visualize their behavior. For this exercise, you need to graph both the original function and its inverse.
Let's break this down:
Let's break this down:
- Plot the original function \(f(x) = \sqrt{x - 3}\). This represents a square root function that's been shifted to the right by 3 units.
- Next, plot the inverse function \(f^{-1}(x) = x^2 + 3\). This is a parabolic function that opens upwards and is shifted upwards by 3 units.
- Use different colors or styles for each graph to easily distinguish between the original function and its inverse.
Reflection over the line y=x
When graphing an original function and its inverse, another important concept to understand is the reflection over the line \(y = x\). This line is often used as a reference because the graph of a function and its inverse are reflections across it.
Consider these key points:
Consider these key points:
- The line \(y = x\) bisects the first and third quadrants of the coordinate plane at a 45-degree angle.
- If you were to fold the graph along this line, the original function's graph would match the inverse function's graph.
- In our example, you'll notice that for every point \((a, b)\) on the graph of the original function, there's a corresponding point \((b, a)\) on the inverse graph.