Question
The table above gives values of a function \( f \) at selected values of \( x \). If \( f \) is twice-differentiable on the interval \( 1 \leq x \leq 5 \), which of the following statements could be true?
\( x \) | 1 | 2 | 3 | 4 | 5 |
---|---|---|---|---|---|
\( f(x) \) | 9 | 4 | 0 | -3 | -5 |
A) \( f’ \) is negative and decreasing for \( 1 \leq x \leq 5 \)
B) \( f’ \) is negative and increasing for \( 1 \leq x \leq 5 \)
C) \( f’ \) is positive and decreasing for \( 1 \leq x \leq 5 \)
D) \( f’ \) is positive and increasing for \( 1 \leq x \leq 5 \)
▶️ Answer/Explanation
Solution
Approximate \( f’ \) using differences: \( f'(x) \approx \frac{f(x+1) – f(x)}{1} \).
\( x = 1 \): \( f'(1) \approx 4 – 9 = -5 \) (negative).
\( x = 2 \): \( f'(2) \approx 0 – 4 = -4 \) (negative).
\( x = 3 \): \( f'(3) \approx -3 – 0 = -3 \) (negative).
\( x = 4 \): \( f'(4) \approx -5 – (-3) = -2 \) (negative).
\( f’ \) is negative. Check \( f” \) (change in \( f’ \)): \( -4 – (-5) = 1 \), \( -3 – (-4) = 1 \), \( -2 – (-3) = 1 \) (positive), so \( f’ \) is increasing.
Answer: B
Final Answer: \( f’ \) is negative and increasing for \( 1 \leq x \leq 5 \)
Question
The graph of the function f is shown above for \(-2\leq x\leq 2\) . Which of the following could be the graph of an antiderivative of f ?
A
B
C
D
▶️Answer/Explanation
Ans:D
Question
The graph of y=h(x) is shown above. Which of the following could be the graph of \(y=h{}'(x)\)?
A
B
C
D
E
▶️Answer/Explanation
Ans:E
Question
The graph of y = f(x) on the closed interval [0, 4] is shown above. Which of the following could be the graph y = f'(x)?
A
B
C
D
E
▶️Answer/Explanation
Ans:D