Math Problem Statement

The graph of y = f(x) is given below. For each of the following questions, use interval notation to enter your answers as open intervals. Part a) On which interval(s) is f'(x) > 0? Part b) On which interval(s) is f'(x) < 0? Part c) On which interval(s) is f''(x) > 0? Part d) On which interval(s) is f''(x) < 0?

Solution

To solve the problem, let's analyze the given graph of f(x)f(x) and determine the intervals for the derivatives f(x)f'(x) and f(x)f''(x).


Step-by-Step Solution:

Part a) On which interval(s) is f(x)>0f'(x) > 0?

The derivative f(x)>0f'(x) > 0 when the graph of f(x)f(x) is increasing. Observing the graph:

  • f(x)f(x) increases from x=1x = 1 to x=3x = 3, and from x=5x = 5 to x=7x = 7.

Thus, f(x)>0f'(x) > 0 on: (1,3),(5,7)(1, 3), (5, 7)


Part b) On which interval(s) is f(x)<0f'(x) < 0?

The derivative f(x)<0f'(x) < 0 when the graph of f(x)f(x) is decreasing. Observing the graph:

  • f(x)f(x) decreases from x=3x = 3 to x=5x = 5.

Thus, f(x)<0f'(x) < 0 on: (3,5)(3, 5)


Part c) On which interval(s) is f(x)>0f''(x) > 0?

The second derivative f(x)>0f''(x) > 0 when the graph of f(x)f(x) is concave up. Observing the graph:

  • f(x)f(x) is concave up from x=4x = 4 to x=7x = 7.

Thus, f(x)>0f''(x) > 0 on: (4,7)(4, 7)


Part d) On which interval(s) is f(x)<0f''(x) < 0?

The second derivative f(x)<0f''(x) < 0 when the graph of f(x)f(x) is concave down. Observing the graph:

  • f(x)f(x) is concave down from x=1x = 1 to x=4x = 4.

Thus, f(x)<0f''(x) < 0 on: (1,4)(1, 4)


Final Answers:

  1. f(x)>0f'(x) > 0: (1,3),(5,7)(1, 3), (5, 7)
  2. f(x)<0f'(x) < 0: (3,5)(3, 5)
  3. f(x)>0f''(x) > 0: (4,7)(4, 7)
  4. f(x)<0f''(x) < 0: (1,4)(1, 4)

Do you want further clarification or a detailed breakdown of any interval?

Relative Questions to Expand Understanding:

  1. How can the concepts of increasing and decreasing functions be related to f(x)>0f'(x) > 0 or f(x)<0f'(x) < 0?
  2. What is the significance of concavity in a graph, and how does it connect to f(x)f''(x)?
  3. How would the answers change if the graph had sharper changes in slope or additional turning points?
  4. How do we find intervals for f(x)=0f'(x) = 0, and what does that signify on a graph?
  5. What are practical applications of determining the intervals where f(x)>0f'(x) > 0 or f(x)>0f''(x) > 0?

Tip:

Always pay attention to the turning points of f(x)f(x) (where f(x)=0f'(x) = 0) and the inflection points (where f(x)=0f''(x) = 0) when analyzing graphs.

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Math Problem Analysis

Mathematical Concepts

Graph Analysis
Derivatives
Concavity

Formulas

f'(x) > 0 for increasing intervals
f'(x) < 0 for decreasing intervals
f''(x) > 0 for concave up
f''(x) < 0 for concave down

Theorems

Rules of Differentiation
Concavity and Inflection Points

Suitable Grade Level

Grades 10-12