Using the second derivative test, how do you find the local maximum and local minimum for #f(x) = x^(3) - 6x^(2) + 5#?

Answer 1

Minimum at x=4 and Maximum at x=0

To begin determining the critical points, solve f'(x)=0.

f '(x)= #3x^2# -12x
Critical points would be known by solving #3x^2# -12x=0. This gives x=0, x=4

Find the second derivative, f"(x) = 6x-12, in order to use the second derivative test.

It would therefore be a minima for x=4 and a maxima for x=0, where f"(x) = 24-12 = 12 (>0).

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Answer 2

To find local maxima and minima using the second derivative test for f(x) = x^3 - 6x^2 + 5:

  1. Find the critical points by setting the first derivative equal to zero and solving for x.
  2. Find the second derivative of f(x).
  3. Evaluate the second derivative at each critical point:
    • If f''(x) > 0, the function has a local minimum at that point.
    • If f''(x) < 0, the function has a local maximum at that point.
    • If f''(x) = 0, the test is inconclusive.

In this case:

  1. The first derivative is f'(x) = 3x^2 - 12x. Setting f'(x) = 0, we get: 3x^2 - 12x = 0 x(3x - 12) = 0 x = 0 or x = 4 So, the critical points are x = 0 and x = 4.

  2. The second derivative is f''(x) = 6x - 12.

  3. Evaluating the second derivative at the critical points:

    • At x = 0: f''(0) = -12 < 0, so there is a local maximum at x = 0.
    • At x = 4: f''(4) = 6(4) - 12 = 12 - 12 = 0, so the test is inconclusive at x = 4.
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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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