Math Problem Statement

Consider the graphed function f(x) = x^2 - 2. 1. Find an equation for the inverse of f(x). 2. Sketch a graph of the inverse of f(x). 3. Is the inverse of f(x) a function? 4. Is f(x) a one-to-one function?

Solution

Let's work through each part of this question step-by-step.

Part (a): Find an equation for the inverse of f(x)f(x).

Given: f(x)=x22f(x) = x^2 - 2 To find the inverse, follow these steps:

  1. Replace f(x)f(x) with yy: y=x22y = x^2 - 2

  2. Swap xx and yy to find the inverse: x=y22x = y^2 - 2

  3. Solve for yy: y2=x+2y^2 = x + 2 y=±x+2y = \pm \sqrt{x + 2}

Thus, the inverse function is: f1(x)=±x+2f^{-1}(x) = \pm \sqrt{x + 2}

However, since the original function f(x)=x22f(x) = x^2 - 2 is not one-to-one (it fails the horizontal line test), its inverse is not a function over the entire domain. We would need to restrict the domain of f(x)f(x) to make the inverse a function.

Part (b): Sketch a graph of the inverse of f(x)f(x).

The graph of the inverse f1(x)=±x+2f^{-1}(x) = \pm \sqrt{x + 2} would look like the reflection of the original parabola over the line y=xy = x. Since we have both +x+2+\sqrt{x + 2} and x+2-\sqrt{x + 2}, the graph will have two branches: one in the positive yy-axis and one in the negative yy-axis, starting from x=2x = -2.

Part (c): Is the inverse of f(x)f(x) a function?

No, the inverse of f(x)f(x) is not a function because it has two values (both +x+2+\sqrt{x + 2} and x+2-\sqrt{x + 2}) for each xx in the domain of the inverse. This violates the definition of a function, which requires that each input has exactly one output.

Part (d): Is f(x)f(x) a one-to-one function?

No, f(x)=x22f(x) = x^2 - 2 is not a one-to-one function because it fails the horizontal line test. For example, f(1)=1f(1) = -1 and f(1)=1f(-1) = -1, so multiple xx-values map to the same yy-value, making it non-invertible over its entire domain.

Would you like a more detailed explanation or have any other questions?


Here are 5 related questions to deepen your understanding:

  1. How can you restrict the domain of f(x)=x22f(x) = x^2 - 2 to make it a one-to-one function?
  2. What is the range of f(x)=x22f(x) = x^2 - 2?
  3. How do we determine if a function has an inverse function?
  4. What does the horizontal line test tell us about functions and their inverses?
  5. How would the graph of the inverse f1(x)f^{-1}(x) change if we restricted f(x)f(x) to only positive values of xx?

Tip: When finding the inverse of a function, always check if the function is one-to-one first. This can save time and clarify whether an inverse function exists over the entire domain.

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Math Problem Analysis

Mathematical Concepts

Inverse functions
Quadratic functions
One-to-one functions
Graph reflections

Formulas

f(x) = x^2 - 2
Inverse function formula

Theorems

Horizontal line test
Definition of a function

Suitable Grade Level

Grades 10-12