Math Problem Statement

Verify that your equation is correct by showing that f(f^-1(x)) = x and f^-1(f(x)) = x cuberoot x-9

Solution

To verify that a function and its inverse are correct, we need to check the conditions:

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

Given the function f(x)=x93f(x) = \sqrt[3]{x - 9}, let's find its inverse f1(x)f^{-1}(x) first.

Finding the Inverse Function f1(x)f^{-1}(x):

  1. Start with the original function: y=x93y = \sqrt[3]{x - 9}
  2. Swap xx and yy to find the inverse: x=y93x = \sqrt[3]{y - 9}
  3. Cube both sides to get rid of the cube root: x3=y9x^3 = y - 9
  4. Solve for yy: y=x3+9y = x^3 + 9

So, the inverse function is: f1(x)=x3+9f^{-1}(x) = x^3 + 9

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

Now, substitute f1(x)f^{-1}(x) into f(x)f(x):

f(f1(x))=f(x3+9)f(f^{-1}(x)) = f(x^3 + 9)

Applying the function ff:

[ f(x^3 + 9) = \sqrt[3]{(x^3 + 9) - 9} = \sqrt[3]{x^3} = x ]

So, f(f1(x))=xf(f^{-1}(x)) = x.

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

Now, substitute f(x)f(x) into f1(x)f^{-1}(x):

f1(f(x))=f1(x93)f^{-1}(f(x)) = f^{-1}(\sqrt[3]{x - 9})

Applying the inverse function f1f^{-1}:

[ f^{-1}(\sqrt[3]{x - 9}) = (\sqrt[3]{x - 9})^3 + 9 = x - 9 + 9 = x ]

So, f1(f(x))=xf^{-1}(f(x)) = x.

Both conditions are satisfied, so the function and its inverse are correct.

Would you like more details or have any questions? Here are some related questions for further exploration:

  1. What is the domain and range of the function f(x)=x93f(x) = \sqrt[3]{x - 9}?
  2. How do you graph the function and its inverse?
  3. How do cube roots affect the shape and properties of the function?
  4. What are the properties of inverse functions in general?
  5. How do you verify inverses of more complex functions?

Tip: When finding inverses, always swap xx and yy, and solve for the new yy. This technique works universally for basic functions.

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Math Problem Analysis

Mathematical Concepts

Inverse Functions
Cube Roots
Function Composition

Formulas

f(x) = \sqrt[3]{x - 9}
f^{-1}(x) = x^3 + 9
f(f^{-1}(x)) = x
f^{-1}(f(x)) = x

Theorems

Properties of Inverse Functions
Function Composition

Suitable Grade Level

Grades 10-12