Math Problem Statement

The function f(x) = ³√(x + 3) - 8 is one-to-one and therefore invertible. Determine f⁻¹. Graph both f and f⁻¹, along with the identity function f(x) = x.

Solution

The problem you're working on involves determining the inverse of the function f(x)=x+338f(x) = \sqrt[3]{x + 3} - 8, graphing both f(x)f(x) and its inverse f1(x)f^{-1}(x), and sketching the identity function f(x)=xf(x) = x on the same graph.

Let's break this down step by step:

Step 1: Finding the Inverse Function

Given f(x)=x+338f(x) = \sqrt[3]{x + 3} - 8, we need to find f1(x)f^{-1}(x).

  1. Start by replacing f(x)f(x) with yy: y=x+338y = \sqrt[3]{x + 3} - 8
  2. Solve for xx in terms of yy: y+8=x+33y + 8 = \sqrt[3]{x + 3}
  3. Cube both sides to eliminate the cube root: (y+8)3=x+3(y + 8)^3 = x + 3
  4. Solve for xx: x=(y+8)33x = (y + 8)^3 - 3

Thus, the inverse function is: f1(x)=(x+8)33f^{-1}(x) = (x + 8)^3 - 3

Step 2: Graphing the Functions

Now that we have the inverse function f1(x)=(x+8)33f^{-1}(x) = (x + 8)^3 - 3, you are asked to plot the following:

  1. The original function f(x)=x+338f(x) = \sqrt[3]{x + 3} - 8.
  2. The inverse function f1(x)=(x+8)33f^{-1}(x) = (x + 8)^3 - 3.
  3. The identity function f(x)=xf(x) = x, which is simply a diagonal line passing through the origin.

Step 3: Characteristics for Graphing

  1. f(x)=x+338f(x) = \sqrt[3]{x + 3} - 8 will have a horizontal shift of 3 units to the left and 8 units down from the basic cube root function.
  2. f1(x)=(x+8)33f^{-1}(x) = (x + 8)^3 - 3 will look like a cubic curve, shifted 8 units to the left and 3 units down.
  3. The identity function f(x)=xf(x) = x is a straight line passing through points like (0, 0), (1, 1), (-1, -1), etc.

If you'd like, I can help you further in plotting these functions or provide more guidance. Let me know if you'd like a detailed visual explanation or further help with graphing!


Relative Questions:

  1. What are the key properties of an inverse function?
  2. How does the graph of a function relate to its inverse geometrically?
  3. What are the transformations applied to f(x)=x3f(x) = \sqrt[3]{x} to get the function f(x)=x+338f(x) = \sqrt[3]{x + 3} - 8?
  4. Why is the identity function f(x)=xf(x) = x important when comparing a function and its inverse?
  5. How can you verify that two functions are inverses of each other algebraically?

Tip:

When graphing a function and its inverse, remember that the two graphs will always be symmetric with respect to the line y=xy = x.

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Math Problem Analysis

Mathematical Concepts

Algebra
Inverse Functions
Graphing Functions

Formulas

f(x) = ³√(x + 3) - 8
f⁻¹(x) = (x + 8)³ - 3

Theorems

Inverse Function Theorem
Reflection over y = x for inverse functions

Suitable Grade Level

Grades 9-12