Math Problem Statement

The function f(x) = x^3 - 11 is one-to-one. Find the inverse f^(-1)(x) and verify that f(f^(-1)(x)) = x and f^(-1)(f(x)) = x.

Solution

Let's analyze the problem step by step.

Given:

The function is f(x)=x311f(x) = x^3 - 11, and you are asked to:

  1. Find the inverse function f1(x)f^{-1}(x).
  2. Verify that the inverse satisfies the conditions f(f1(x))=xf(f^{-1}(x)) = x and f1(f(x))=xf^{-1}(f(x)) = x.

Part a: Find the inverse function

To find the inverse function f1(x)f^{-1}(x), follow these steps:

  1. Start with the equation for the function: y=x311y = x^3 - 11
  2. Swap xx and yy to reflect that we are finding the inverse: x=y311x = y^3 - 11
  3. Solve for yy: x+11=y3x + 11 = y^3 y=x+113y = \sqrt[3]{x + 11}

Thus, the inverse function is: f1(x)=x+113f^{-1}(x) = \sqrt[3]{x + 11}

This corresponds to choice C in the options.

Part b: Verify the inverse function

Now, you need to verify that the inverse function satisfies the conditions.

1. Verify f(f1(x))=xf(f^{-1}(x)) = x:

f(f1(x))=f(x+113)f(f^{-1}(x)) = f\left(\sqrt[3]{x + 11}\right) Substitute x+113\sqrt[3]{x + 11} into f(x)=x311f(x) = x^3 - 11: [ f\left(\sqrt[3]{x + 11}\right) = \left(\sqrt[3]{x + 11}\right)^3 - 11 = (x + 11) - 11 = x ] So, f(f1(x))=xf(f^{-1}(x)) = x, which is verified.

2. Verify f1(f(x))=xf^{-1}(f(x)) = x:

f1(f(x))=f1(x311)f^{-1}(f(x)) = f^{-1}(x^3 - 11) Substitute x311x^3 - 11 into f1(x)=x+113f^{-1}(x) = \sqrt[3]{x + 11}: [ f^{-1}(x^3 - 11) = \sqrt[3]{(x^3 - 11) + 11} = \sqrt[3]{x^3} = x ] Thus, f1(f(x))=xf^{-1}(f(x)) = x, which is also verified.

Conclusion

The inverse function f1(x)=x+113f^{-1}(x) = \sqrt[3]{x + 11} satisfies both conditions, confirming the correctness.

Would you like more details, or do you have any further questions?


Here are 5 related questions to expand on this concept:

  1. How do you find the domain and range of inverse functions?
  2. What are some real-world applications of inverse functions?
  3. Can all cubic functions have an inverse function?
  4. How would the process change if the original function was not one-to-one?
  5. What are some graphical ways to verify that a function and its inverse are correct?

Tip: Always check whether the original function is one-to-one before finding the inverse.

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Math Problem Analysis

Mathematical Concepts

Inverse Functions
Cubic Functions

Formulas

f(x) = x^3 - 11
f^(-1)(x) = (x + 11)^(1/3)

Theorems

Inverse function theorem
One-to-one function

Suitable Grade Level

Grades 10-12