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Ch. 4 - Applications of Derivatives
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 4, Problema 4.4.110

110. Suppose the derivative of the function y = f(x) is
y'=(x-1)^22(x-2)(x-4).
At what points, if any, does the graph of f have a local minimum, local maximum, or
point of inflection?

Guida verificata passo dopo passo
1
Step 1: Identify critical points by setting the derivative y' = (x-1)^2 * 2(x-2)(x-4) equal to zero. Solve for x to find the values where the slope of the tangent line is zero or undefined.
Step 2: Analyze the multiplicity of the factors in y'. For example, (x-1)^2 has even multiplicity, which means it does not change sign at x = 1. Factors with odd multiplicity, such as (x-2) and (x-4), indicate sign changes at x = 2 and x = 4.
Step 3: Use the first derivative test to determine whether each critical point corresponds to a local minimum, local maximum, or neither. Examine the sign of y' on intervals around each critical point (e.g., test values in intervals like (−∞, 1), (1, 2), (2, 4), and (4, ∞)).
Step 4: To find points of inflection, compute the second derivative y'' by differentiating y' = (x-1)^2 * 2(x-2)(x-4). Set y'' equal to zero and solve for x to identify where the concavity changes.
Step 5: Verify the nature of each point of inflection by checking the sign of y'' on intervals around the solutions obtained in Step 4. Points where y'' changes sign indicate points of inflection.

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Derivative and Critical Points

The derivative of a function, denoted as y' or f'(x), represents the rate of change of the function at any point. Critical points occur where the derivative is zero or undefined, indicating potential local maxima, minima, or points of inflection. To find these points, we set the derivative equal to zero and solve for x.
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Critical Points

Second Derivative Test

The second derivative test is a method used to determine the nature of critical points. If the second derivative, f''(x), is positive at a critical point, the function has a local minimum; if negative, it has a local maximum. If the second derivative is zero, the test is inconclusive, and further analysis is needed.
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The Second Derivative Test: Finding Local Extrema

Points of Inflection

Points of inflection occur where the concavity of the function changes, which can be identified by analyzing the second derivative. Specifically, a point of inflection exists where f''(x) changes sign, indicating a transition from concave up to concave down or vice versa. These points are important for understanding the overall shape of the graph.
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Critical Points
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