Math Problem Statement

The function f is given by f (x) = –3x6 + 4x2 + x + 8. Which of the following statements is true? The polynomial f has one global minimum and one global maximum. The polynomial f has one global minimum. The polynomial f has no global extrema. The polynomial f has one global maximum.

Solution

To determine the correct statement about the polynomial function f(x)=3x6+4x2+x+8f(x) = -3x^6 + 4x^2 + x + 8, we need to analyze the function's behavior using calculus, specifically by finding its critical points and analyzing the second derivative for concavity.

Step 1: First Derivative (Critical Points)

The first derivative helps us find the critical points of the function, which are potential locations for local maxima or minima.

f(x)=ddx(3x6+4x2+x+8)f'(x) = \frac{d}{dx}(-3x^6 + 4x^2 + x + 8) f(x)=18x5+8x+1f'(x) = -18x^5 + 8x + 1

We find critical points by setting f(x)=0f'(x) = 0:

18x5+8x+1=0-18x^5 + 8x + 1 = 0

This is a quintic equation (degree 5), and finding exact solutions algebraically can be difficult. However, the general behavior of this equation gives us insight into the number of critical points.

Step 2: Second Derivative (Concavity)

We now compute the second derivative to analyze concavity and determine whether the critical points correspond to maxima or minima.

f(x)=ddx(18x5+8x+1)f''(x) = \frac{d}{dx}(-18x^5 + 8x + 1) f(x)=90x4+8f''(x) = -90x^4 + 8

Step 3: Behavior of the Polynomial

  • The highest-degree term in f(x)f(x) is 3x6-3x^6, which is a negative even power. This means that as xx \to \infty or xx \to -\infty, the function tends toward -\infty.
  • Therefore, the function does not have a global maximum because it decreases without bound for large positive and large negative xx.

However, since the function is a degree-6 polynomial and exhibits downward opening behavior at the ends, there is likely a global minimum somewhere between these regions.

Conclusion:

The correct statement is:

The polynomial ff has one global minimum.

Would you like more details on how the critical points or concavity work here?


Here are 5 related questions to explore this concept further:

  1. How do you determine local extrema using the first and second derivatives?
  2. What is the significance of a polynomial's highest-degree term in its behavior at infinity?
  3. How can quintic equations like 18x5+8x+1=0-18x^5 + 8x + 1 = 0 be solved numerically?
  4. How does the second derivative test help classify critical points?
  5. What role does symmetry play in the analysis of polynomial functions?

Tip: The sign of the leading coefficient of a polynomial determines whether it opens upwards or downwards.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Calculus
Polynomial Functions
Critical Points
Concavity

Formulas

First derivative: f'(x) = -18x^5 + 8x + 1
Second derivative: f''(x) = -90x^4 + 8

Theorems

Second Derivative Test
Behavior of polynomials based on leading term

Suitable Grade Level

Grades 11-12