Math Problem Statement

A function g(x) is given by g(x) = x^4 - 6x^2 + 9. Where does the local maximum occur?

Solution

To find where the local maximum of the function g(x)=x46x2+9g(x) = x^4 - 6x^2 + 9 occurs, we need to follow these steps:

1. Find the first derivative of the function:

g(x)=ddx(x46x2+9)g'(x) = \frac{d}{dx}(x^4 - 6x^2 + 9) g(x)=4x312xg'(x) = 4x^3 - 12x

2. Set the first derivative equal to zero to find critical points:

4x312x=04x^3 - 12x = 0 Factor the equation: 4x(x23)=04x(x^2 - 3) = 0 Set each factor equal to zero: 4x=0x=04x = 0 \quad \Rightarrow \quad x = 0 x23=0x=±3x^2 - 3 = 0 \quad \Rightarrow \quad x = \pm\sqrt{3}

So, the critical points are x=0x = 0, x=3x = \sqrt{3}, and x=3x = -\sqrt{3}.

3. Determine the nature of each critical point using the second derivative:

Find the second derivative g(x)g''(x): g(x)=ddx(4x312x)g''(x) = \frac{d}{dx}(4x^3 - 12x) g(x)=12x212g''(x) = 12x^2 - 12

Evaluate g(x)g''(x) at each critical point:

  • At x=0x = 0: g(0)=12(0)212=12(Negative, indicating a local maximum)g''(0) = 12(0)^2 - 12 = -12 \quad (\text{Negative, indicating a local maximum})
  • At x=3x = \sqrt{3} and x=3x = -\sqrt{3}: g(3)=12(3)212=12(3)12=3612=24(Positive, indicating local minima)g''(\sqrt{3}) = 12(\sqrt{3})^2 - 12 = 12(3) - 12 = 36 - 12 = 24 \quad (\text{Positive, indicating local minima})

4. Conclusion:

The local maximum occurs at x=0x = 0.

Would you like to explore more details, or do you have any questions?

Here are some related questions:

  1. How do you determine if a critical point is a local maximum, minimum, or a saddle point?
  2. What is the significance of the second derivative test in finding local extrema?
  3. Can a function have more than one local maximum or minimum?
  4. How do the coefficients of a polynomial function influence the location and nature of critical points?
  5. What is the relationship between the degree of a polynomial and the number of critical points?

Tip: The second derivative test is a quick way to determine the nature of a critical point: if g(x)g''(x) is negative at a critical point, it's a local maximum; if positive, it's a local minimum.

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Math Problem Analysis

Mathematical Concepts

Calculus
Derivatives
Critical Points
Local Extrema

Formulas

First derivative
Second derivative test

Theorems

Second Derivative Test

Suitable Grade Level

Advanced High School / College