Math Problem Statement

Consider the function g(x) = x^4 - 4x^3 + 10. Which one of the following statements is true regarding the extreme values of g(x) on the interval (-∞, ∞)?

Solution

To determine the correct answer, let's analyze the function g(x)=x44x3+10g(x) = x^4 - 4x^3 + 10 by finding its critical points and determining the nature of these points.

Step 1: Find the derivative g(x)g'(x)

The derivative of g(x)g(x) is: g(x)=4x312x2g'(x) = 4x^3 - 12x^2 Factoring out 4x24x^2 gives: g(x)=4x2(x3)g'(x) = 4x^2(x - 3) Setting g(x)=0g'(x) = 0 to find the critical points: 4x2(x3)=04x^2(x - 3) = 0 This results in: x=0orx=3x = 0 \quad \text{or} \quad x = 3

Step 2: Determine the nature of the critical points

To identify whether each critical point is a local maximum or minimum, we can use the second derivative test.

Find g(x)g''(x):

g(x)=12x224xg''(x) = 12x^2 - 24x Factoring gives: g(x)=12x(x2)g''(x) = 12x(x - 2)

Now we evaluate g(x)g''(x) at x=0x = 0 and x=3x = 3:

  • At x=0x = 0: g(0)=120(02)=0g''(0) = 12 \cdot 0 \cdot (0 - 2) = 0 Since g(0)=0g''(0) = 0, the second derivative test is inconclusive for x=0x = 0.

  • At x=3x = 3: g(3)=123(32)=1231=36g''(3) = 12 \cdot 3 \cdot (3 - 2) = 12 \cdot 3 \cdot 1 = 36 Since g(3)>0g''(3) > 0, this indicates a local minimum at x=3x = 3.

Conclusion

Based on this analysis:

  • There is a local minimum at x=3x = 3.
  • The critical point at x=0x = 0 is inconclusive, but it does not indicate a local maximum or minimum for this analysis.

Thus, the correct answer is: The function has only a local minimum at x=3x = 3.

Would you like further details on any part of this solution? Here are some related questions for further exploration:

  1. How can we confirm if x=0x = 0 is a point of inflection?
  2. What is the behavior of g(x)g(x) as xx \to \infty or xx \to -\infty?
  3. How would we approach finding global extrema on a closed interval instead of (,)(-\infty, \infty)?
  4. Could we use the first derivative test to analyze the nature of critical points instead of the second derivative test?
  5. How does the shape of the graph of g(x)g(x) help in understanding its extrema?

Tip: For polynomial functions, always start by finding the derivative and setting it to zero to locate critical points. This approach helps identify potential maxima, minima, or points of inflection.

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Math Problem Analysis

Mathematical Concepts

Calculus
Derivatives
Critical Points
Second Derivative Test

Formulas

g'(x) = 4x^3 - 12x^2
g''(x) = 12x^2 - 24x

Theorems

Second Derivative Test

Suitable Grade Level

Grades 11-12