Math Problem Statement

Analyze the functions f(x) = x(x + 1)^2 and g(x) = (x - 4)^2 to determine their injectivity and surjectivity.

Solution

The image presents two parts, labeled (a) and (b), that require analyzing two different functions to complete specific statements. Let’s break down each part.

Part (a)

The function ff is defined as: f:R0+R,f(x)=x(x+1)2f : \mathbb{R}^+_0 \to \mathbb{R}, \quad f(x) = x(x + 1)^2

  • The function maps from the set of non-negative real numbers R0+\mathbb{R}^+_0 to the real numbers R\mathbb{R}.
  • You need to identify the characteristics of the equation f(x)=x(x+1)2f(x) = x(x + 1)^2, such as its behavior or properties like injectivity or surjectivity, in order to complete the statement.

We need to analyze whether f(x)f(x) has a specific property (e.g., injectivity, surjectivity, or both) and then conclude whether ff is injective, surjective, or bijective.

Part (b)

The function gg is defined as: g:R0+R0+,g(x)=(x4)2g : \mathbb{R}^+_0 \to \mathbb{R}^+_0, \quad g(x) = (x - 4)^2

  • The function maps from the set of non-negative real numbers to itself.
  • Similarly to part (a), the statement requires determining the properties of g(x)=(x4)2g(x) = (x - 4)^2 and concluding whether gg is injective, surjective, or both.

Steps to Solve:

  1. Analyze Function f(x)=x(x+1)2f(x) = x(x + 1)^2 (Part a):

    • Investigate injectivity: Check whether different inputs x1x_1 and x2x_2 can give the same output.
    • Investigate surjectivity: Determine if every value in the target space R\mathbb{R} has a pre-image in the domain.
  2. Analyze Function g(x)=(x4)2g(x) = (x - 4)^2 (Part b):

    • For injectivity: Determine if distinct values of xx lead to distinct outputs.
    • For surjectivity: Check whether every non-negative real number has a pre-image.

Let me know if you would like a detailed breakdown of these analyses! Would you also like to know more about the behavior of these types of functions in general?


Here are five questions you can explore further:

  1. What is the definition of an injective function?
  2. How can you determine if a function is surjective?
  3. What is the geometric interpretation of f(x)=x(x+1)2f(x) = x(x + 1)^2?
  4. How does the function g(x)=(x4)2g(x) = (x - 4)^2 behave for values of xx close to 4?
  5. What is the relationship between injectivity, surjectivity, and bijectivity?

Tip:

When determining injectivity, try plugging in two different values for xx and see if their outputs can ever be equal.

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Math Problem Analysis

Mathematical Concepts

Functions
Injectivity
Surjectivity
Quadratic Functions

Formulas

f(x) = x(x + 1)^2
g(x) = (x - 4)^2

Theorems

Injective function: A function is injective if f(x1) = f(x2) implies x1 = x2.
Surjective function: A function is surjective if for every y in the codomain, there exists an x in the domain such that f(x) = y.

Suitable Grade Level

Grades 10-12