Math Problem Statement

Describe the long run behavior of f(n) = -2(3)^n + 4: As n → ∞, f(n) → ? As n → -∞, f(n) → ?

Solution

To analyze the problem from the image:

The function provided is:
f(n)=2(3)n+4f(n) = -2(3)^n + 4

We are tasked with describing the long-run behavior of f(n)f(n), which involves understanding what happens to f(n)f(n) as nn \to \infty (as nn becomes very large) and nn \to -\infty (as nn becomes very negative). Here's how to proceed:


1. Behavior as nn \to \infty:

  • The term 3n3^n grows exponentially as nn \to \infty. Thus, 2(3)n-2(3)^n grows negatively without bound (it approaches -\infty).
  • Adding 4 does not significantly change this behavior, as the 2(3)n-2(3)^n term dominates.
    As n,f(n).\text{As } n \to \infty, f(n) \to -\infty.

2. Behavior as nn \to -\infty:

  • When nn \to -\infty, 3n=(31)n=(13)n3^n = (3^{-1})^n = \left(\frac{1}{3}\right)^n, which approaches 0 because powers of fractions decrease rapidly. Thus, 2(3)n0-2(3)^n \to 0.
  • Adding 4 means the result approaches: As n,f(n)4.\text{As } n \to -\infty, f(n) \to 4.

Final Answer:

  • As nn \to \infty, f(n)f(n) \to -\infty.
  • As nn \to -\infty, f(n)4f(n) \to 4.

Let me know if you'd like further clarification or a detailed breakdown! 😊


Related Questions:

  1. What are the general rules for determining the end behavior of exponential functions?
  2. How does changing the base of the exponential term affect the growth rate?
  3. How does the coefficient 2-2 impact the function's range and direction?
  4. What happens to f(n)f(n) if we change +4+4 to 4-4?
  5. How would the behavior of f(n)f(n) change if the base 3n3^n were replaced by (1/2)n(1/2)^n?

Tip:

When analyzing the long-run behavior of functions, focus on the term with the highest growth rate as nn \to \infty or nn \to -\infty, and consider how the sign and constants affect the outcome.

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Math Problem Analysis

Mathematical Concepts

Exponential Functions
Limits
Asymptotic Behavior

Formulas

f(n) = -2(3)^n + 4

Theorems

Properties of Exponential Growth

Suitable Grade Level

Grades 10-12