Math Problem Statement

Refer to the graph of the derivative f'(x) of a function on the interval (0,8) and answer questions about the behavior of f(x), including intervals where it is increasing, concave down, and locations of local minima and inflection points.

Solution

To analyze this graph and answer the questions, we need to interpret the behavior of the derivative f(x)f'(x) and what it implies about the original function f(x)f(x) on the interval (0,8)(0,8).

Let's go through each part:

(A) For what values of xx in (0,8)(0,8) is f(x)f(x) increasing?

  • Explanation: f(x)f(x) is increasing where f(x)>0f'(x) > 0 (where the derivative is positive).
  • Analysis: Looking at the graph, f(x)>0f'(x) > 0 in the intervals (1,2)(1, 2), (3,4.5)(3, 4.5), and (6,8)(6, 8).
  • Answer: (1,2)(3,4.5)(6,8)(1, 2) \cup (3, 4.5) \cup (6, 8)

(B) For what values of xx in (0,8)(0,8) is f(x)f(x) concave down?

  • Explanation: f(x)f(x) is concave down where f(x)f'(x) is decreasing (the slope of f(x)f'(x) is negative).
  • Analysis: From the graph, f(x)f'(x) is decreasing over the intervals (0.5,1.5)(0.5, 1.5), (2.5,3.5)(2.5, 3.5), and (5,6.5)(5, 6.5).
  • Answer: (0.5,1.5)(2.5,3.5)(5,6.5)(0.5, 1.5) \cup (2.5, 3.5) \cup (5, 6.5)

(C) Find all values of xx in (0,8)(0,8) where f(x)f(x) has a local minimum.

  • Explanation: A local minimum in f(x)f(x) occurs where f(x)f'(x) changes from negative to positive, passing through zero.
  • Analysis: From the graph, f(x)f'(x) changes from negative to positive at x=1.5x = 1.5 and x=6x = 6.
  • Answer: 1.5,61.5, 6

(D) Find all values of xx in (0,8)(0,8) where f(x)f(x) has an inflection point.

  • Explanation: Inflection points occur where f(x)f(x) changes concavity, which happens where f(x)f'(x) changes from increasing to decreasing or vice versa.
  • Analysis: Observing the graph, inflection points are at x=1x = 1, x=3x = 3, x=4.5x = 4.5, and x=6.5x = 6.5.
  • Answer: 1,3,4.5,6.51, 3, 4.5, 6.5

Would you like more details on any specific part of this solution, or do you have additional questions?

Here are five related questions to expand on this information:

  1. How do we interpret the behavior of f(x)f(x) given only the graph of f(x)f'(x)?
  2. What is the significance of an interval where f(x)=0f'(x) = 0 but does not change sign?
  3. How would you identify points of inflection if given the second derivative, f(x)f''(x), instead?
  4. Can a function have a local extremum without the derivative being zero? Under what conditions?
  5. What does it mean if f(x)f'(x) has a sharp corner at a point, and how does it affect f(x)f(x)?

Tip: When examining a derivative graph, always look at where it crosses the x-axis and whether it’s increasing or decreasing, as these details reveal the function's critical points and concavity.

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Math Problem Analysis

Mathematical Concepts

Calculus
Derivative Analysis
Increasing/Decreasing Functions
Concavity
Inflection Points
Local Extrema

Formulas

f(x) is increasing where f'(x) > 0
f(x) is concave down where f'(x) is decreasing
Local minima where f'(x) changes from negative to positive
Inflection points where concavity changes

Theorems

First Derivative Test
Second Derivative Test

Suitable Grade Level

Grades 11-12