Math Problem Statement

Suppose that the second derivative of a function f is given by f''(x) = x^2 (x - 2)^4 (x - 3)^2. Find the x-coordinates of the inflection points of f (if any).

Solution

The given second derivative of the function ff is:

f(x)=x2(x2)4(x3)2f''(x) = x^2(x - 2)^4(x - 3)^2

To find the inflection points, we need to check where f(x)=0f''(x) = 0 and analyze the sign changes of f(x)f''(x) around those points. Inflection points occur where the concavity of the function changes, i.e., where f(x)f''(x) changes sign.

Step 1: Solve f(x)=0f''(x) = 0

Set f(x)=0f''(x) = 0:

x2(x2)4(x3)2=0x^2(x - 2)^4(x - 3)^2 = 0

This equation will be zero when any factor equals zero. So, solve for each factor:

  • x2=0x^2 = 0 gives x=0x = 0.
  • (x2)4=0(x - 2)^4 = 0 gives x=2x = 2.
  • (x3)2=0(x - 3)^2 = 0 gives x=3x = 3.

Thus, the possible inflection points are x=0x = 0, x=2x = 2, and x=3x = 3.

Step 2: Analyze sign changes of f(x)f''(x)

To confirm that these points are inflection points, check whether f(x)f''(x) changes sign around these points.

  1. At x=0x = 0:

    • For x<0x < 0, x2>0x^2 > 0, and the other factors are positive, so f(x)>0f''(x) > 0.
    • For x>0x > 0, x2>0x^2 > 0, and the other factors are still positive, so f(x)>0f''(x) > 0.

    There is no sign change at x=0x = 0, so it is not an inflection point.

  2. At x=2x = 2:

    • For x<2x < 2, the factor (x2)4>0(x - 2)^4 > 0, and the other factors are positive, so f(x)>0f''(x) > 0.
    • For x>2x > 2, the factor (x2)4>0(x - 2)^4 > 0, and the other factors remain positive, so f(x)>0f''(x) > 0.

    There is no sign change at x=2x = 2, so it is not an inflection point.

  3. At x=3x = 3:

    • For x<3x < 3, (x3)2>0(x - 3)^2 > 0, so f(x)>0f''(x) > 0.
    • For x>3x > 3, (x3)2>0(x - 3)^2 > 0, so f(x)>0f''(x) > 0.

    There is no sign change at x=3x = 3, so it is not an inflection point.

Conclusion:

There are no inflection points for this function because f(x)f''(x) does not change sign at x=0x = 0, x=2x = 2, or x=3x = 3.

The correct answer is (A) none.


Would you like further details or have any questions?

Here are 5 related questions for you:

  1. What are inflection points, and why do they require a sign change in f(x)f''(x)?
  2. Can a point where f(x)=0f''(x) = 0 always be considered an inflection point?
  3. How does the multiplicity of a root affect whether f(x)f''(x) changes sign at that point?
  4. What are the typical steps for finding concavity and inflection points in functions?
  5. What is the difference between a critical point and an inflection point?

Tip: Always check sign changes of the second derivative when identifying inflection points, as not all zeros of f(x)f''(x) lead to inflection points.

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Math Problem Analysis

Mathematical Concepts

Inflection Points
Concavity
Second Derivative

Formulas

f''(x) = x^2 (x - 2)^4 (x - 3)^2

Theorems

Inflection points occur when f''(x) changes sign

Suitable Grade Level

Grade 12 or university level