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Multiple Choice
Suppose the graph of is shown below. At which of the following intervals is ?
A
Where the graph of has a local maximum
B
Where the graph of is concave down
C
Where the graph of is concave up
D
Where the graph of is decreasing
Verified step by step guidance
1
Step 1: Understand the meaning of f''(x) > 0. The second derivative, f''(x), represents the concavity of the graph of f(x). When f''(x) > 0, the graph of f(x) is concave up, meaning it curves upwards like a U-shape.
Step 2: Analyze the relationship between concavity and the graph of f(x). A graph is concave up when the slope of f'(x) (the first derivative) is increasing. This corresponds to f''(x) > 0.
Step 3: Examine the given options. The correct answer is 'Where the graph of f(x) is concave up,' because this directly corresponds to f''(x) > 0. The other options do not align with the condition f''(x) > 0: (a) A local maximum occurs when f'(x) = 0 and f''(x) < 0, (b) Concave down corresponds to f''(x) < 0, and (c) Decreasing corresponds to f'(x) < 0, not f''(x).
Step 4: Relate the concept of concavity to the graph visually. If you were looking at the graph of f(x), identify intervals where the curve bends upwards. These intervals are where f''(x) > 0.
Step 5: Conclude that the correct intervals for f''(x) > 0 are those where the graph of f(x) is concave up. This is the key takeaway for understanding the relationship between the second derivative and the graph's shape.