Math Problem Statement

Test for relative maxima and minima. Use the​ second-derivative test, if possible. yequalsxcubedminus12xplus3 Question content area bottom Part 1 Select the correct choice below​ and, if​ necessary, fill in the answer​ box(es) to complete your choice. A. The relative maxima occur at xequals    enter your response here. The relative minima occur at    enter your response here. ​(Type integers or simplified fractions. Use a comma to separate answers as​ needed.) B. The relative maxima occur at xequals    enter your response here. There are no relative minima. ​(Type an integer or a simplified fraction. Use a comma to separate answers as​ needed.) C. The relative minima occur at xequals    enter your response here. There are no relative maxima. ​(Type an integer or a simplified fraction. Use a comma to separate answers as​ needed.) D. There are no relative maxima and no relative minima.

Solution

To solve this problem, we will use the second-derivative test on the function y=x312x+3y = x^3 - 12x + 3.

Step 1: Find the first derivative

The first derivative yy' gives us the critical points, where relative maxima or minima might occur:

y=ddx(x312x+3)=3x212y' = \frac{d}{dx}(x^3 - 12x + 3) = 3x^2 - 12

Step 2: Set the first derivative equal to zero

To find the critical points, we solve y=0y' = 0:

3x212=03x^2 - 12 = 0

x2=4x^2 = 4

x=±2x = \pm 2

So, the critical points are x=2x = 2 and x=2x = -2.

Step 3: Find the second derivative

The second derivative yy'' helps us determine the concavity at these critical points:

y=ddx(3x212)=6xy'' = \frac{d}{dx}(3x^2 - 12) = 6x

Step 4: Apply the second-derivative test

  • At x=2x = 2, we compute y(2)y''(2): y(2)=6(2)=12y''(2) = 6(2) = 12 Since y(2)>0y''(2) > 0, the function is concave up at x=2x = 2, meaning this is a relative minimum.

  • At x=2x = -2, we compute y(2)y''(-2): y(2)=6(2)=12y''(-2) = 6(-2) = -12 Since y(2)<0y''(-2) < 0, the function is concave down at x=2x = -2, meaning this is a relative maximum.

Step 5: Conclusion

  • Relative maximum occurs at x=2x = -2.
  • Relative minimum occurs at x=2x = 2.

Thus, the correct answer is:

Choice A: The relative maxima occur at x=2x = -2. The relative minima occur at x=2x = 2.


Would you like more details or have any questions?

Here are 5 related questions to consider:

  1. What is the absolute maximum and minimum of this function?
  2. How do you use the first-derivative test to confirm relative extrema?
  3. Can you find the inflection points of the function y=x312x+3y = x^3 - 12x + 3?
  4. What is the behavior of the function as xx \to \infty and xx \to -\infty?
  5. How do the first and second derivatives relate to the graph of the function?

Tip: Always check the concavity at critical points using the second derivative for better insight into the function's behavior.

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Math Problem Analysis

Mathematical Concepts

Calculus
Critical Points
Relative Maxima and Minima
Second Derivative Test

Formulas

First derivative: y' = 3x^2 - 12
Second derivative: y'' = 6x

Theorems

Second Derivative Test

Suitable Grade Level

Grades 10-12