Math Problem Statement

Use the function f(x)=x3−1 with its graph shown below to answer the following question. Two of the following statements are true. Select the two that apply. The function f and its inverse are reflections over the line y=x .

The function f and its inverse both have minimum and maximum values.

The function f and its inverse are symmetric around the same point.

The function f and its inverse are both increasing functions.

Solution

Let's analyze the function f(x)=x31f(x) = x^3 - 1 and its inverse to identify the two correct statements.

1. Reflection over the line y=xy = x:

  • A function and its inverse are always reflections of each other over the line y=xy = x. So, this statement is true.
  • True statement: The function ff and its inverse are reflections over the line y=xy = x.

2. Minimum and maximum values:

  • The function f(x)=x31f(x) = x^3 - 1 is a cubic function, which is monotonic and has no minimum or maximum values (it goes to -\infty as xx \to -\infty and \infty as xx \to \infty).
  • Its inverse, therefore, will also not have minimum or maximum values.
  • False statement: The function ff and its inverse both have minimum and maximum values.

3. Symmetry around the same point:

  • The function f(x)=x31f(x) = x^3 - 1 is neither symmetric around a point nor has any symmetry about a line (except for the reflection over y=xy = x with its inverse). So, this is false.
  • False statement: The function ff and its inverse are symmetric around the same point.

4. Both functions are increasing:

  • The function f(x)=x31f(x) = x^3 - 1 is an increasing function because its derivative f(x)=3x2f'(x) = 3x^2 is always positive for all xx. Since the inverse of a strictly increasing function is also strictly increasing, the inverse function will also be increasing.
  • True statement: The function ff and its inverse are both increasing functions.

Correct Statements:

  1. The function ff and its inverse are reflections over the line y=xy = x.
  2. The function ff and its inverse are both increasing functions.

Would you like more details or have any questions?

Here are some related questions to explore:

  1. What is the derivative of the inverse function of f(x)=x31f(x) = x^3 - 1?
  2. How do you compute the inverse of a cubic function like f(x)=x31f(x) = x^3 - 1?
  3. What does it mean for a function to be monotonic?
  4. What are the graphical properties of functions and their inverses?
  5. How do reflections across the line y=xy = x affect the graph of a function?

Tip: A function's inverse only exists if the function is one-to-one (i.e., it passes the horizontal line test).

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Math Problem Analysis

Mathematical Concepts

Cubic Functions
Inverse Functions
Reflections
Monotonicity

Formulas

f(x) = x^3 - 1
f'(x) = 3x^2

Theorems

Inverse Function Theorem
Monotonicity and Inverses
Reflection over y = x

Suitable Grade Level

Grades 10-12