Chapter 8: Problem 32
Find the inverse function. $$ h(x)=\sqrt[3]{x+3} $$
Short Answer
Expert verified
Answer: The inverse function of h(x) is h^(-1)(x) = x^3 - 3.
Step by step solution
01
Switch x and h(x) positions
We will switch x and h(x) positions in the equation. So, we will have:
$$
x=\sqrt[3]{h(x)+3}
$$
02
Solve for the new x
To find the new x expression, we will raise both sides of the equation to the power of 3, to undo the cube root on the right side:
$$
(x)^3 = (\sqrt[3]{h(x) +3})^3
$$
The cube and the cube root cancel each other out:
$$
x^3 = h(x)+3
$$
Now, we can isolate h(x) by subtracting 3 from both sides:
$$
h(x) = x^3 - 3
$$
03
Write the expression for the inverse function h^(-1)(x)
Since we have solved for h(x) in terms of x, we can now write the expression for the inverse function, h^(-1)(x):
$$
h^(-1)(x) = x^3 - 3
$$
Therefore, the inverse function of h(x) is:
$$
h^(-1)(x) = x^3 - 3
$$
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cube Root
The cube root of a number is a special type of root. It involves finding a value that, when multiplied by itself three times, equals the original number. For example, the cube root of 27 is 3 because when we multiply 3 by itself three times (3 × 3 × 3), we get 27. In algebra, this is written as \( \sqrt[3]{27} = 3 \). Cube roots are denoted by the radical symbol with a small 3, like this: \( \sqrt[3]{x} \).
Cube roots operate differently compared to square roots. They can yield both positive and negative results. For example, \( \sqrt[3]{-8} = -2 \) because \(-2 \times -2 \times -2 = -8\).
This concept is useful in inverse functions, especially in cases where we need to "undo" a cube operation to solve for a particular variable.
Cube roots operate differently compared to square roots. They can yield both positive and negative results. For example, \( \sqrt[3]{-8} = -2 \) because \(-2 \times -2 \times -2 = -8\).
This concept is useful in inverse functions, especially in cases where we need to "undo" a cube operation to solve for a particular variable.
Function Transformation
Function transformations refer to shifting, stretching, or compressing the graph of a function. There are several ways that functions can be transformed:
Understanding these transformations aids in visualizing what the function looks like on a graph, which is crucial for topics like inverse functions.
- Translation: This involves moving the graph of a function up, down, left, or right. For instance, adding or subtracting a constant value inside the radical will move the cube root function horizontally. In our exercise, \( h(x)=\sqrt[3]{x+3} \) involves a horizontal shift. The function is shifted 3 units to the left because we added 3 to the \( x \) inside the cube root.
- Vertical transformation: Adjusting the function by adding to or multiplying by a constant outside will move it up or down. For example, if there was an addition or subtraction outside the cube root, it would shift the graph up or down, respectively.
- Reflection and Dilations: These involve flipping a graph over an axis or changing its steepness, but are not present in this specific problem.
Understanding these transformations aids in visualizing what the function looks like on a graph, which is crucial for topics like inverse functions.
Algebraic Manipulation
Algebraic manipulation involves rearranging and simplifying equations or expressions to solve for a variable. It is a foundational skill in algebra that helps balance and simplify functions.
Mastering algebraic manipulation techniques provides the tools needed to handle complex functions and their inverses, enabling students to solve a broad range of mathematical problems.
- Switching Variables: As shown in the step-by-step solution, we begin finding the inverse function by swapping \( x \) and \( h(x) \). This is because inverse functions essentially "reverse" the roles of input and output.
- Using Operations to Isolate Variables: When the cube root is involved, raising both sides by the power of 3 helps eliminate the radical. The operation cancels out the cube root, leading to the simpler \( h(x) + 3 = x^3\).
- Solving for \( h(x) \): Finally, you isolate \( h(x) \) by performing simple algebraic operations like subtraction. These steps are necessary to rewrite the function in terms of the new variable \( x \).
Mastering algebraic manipulation techniques provides the tools needed to handle complex functions and their inverses, enabling students to solve a broad range of mathematical problems.