The graph of a twice-differentiable function

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To determine the graph of a twice-differentiable function, it is essential to analyze the intervals where the first derivative is positive or negative. The discussion highlights a potential typographical error in the problem statement, suggesting that "x < 2" should actually read "x < -2" to maintain consistency with the properties of the function. This correction implies that the function is increasing for x < -2, contradicting the original assertion that it is decreasing in that interval. The participants emphasize that understanding these derivative properties is crucial for accurately determining the function's behavior. Clarifying this error is key to solving the problem correctly.
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Homework Statement


How to determine the graph using the properties of a twice-differentiable function ?
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Homework Equations


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The Attempt at a Solution


when x < 2 , y ' > 0 . So, the function is increasing on this interval. But , the correct answer is ( D) and the function is decreasing when x < 2.
Could somebody help me to solve this problem ?
Thank you for your help
 

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The top line in the problem must be an error. To be consistent with the rest of the problem, it should read x < -2.
 
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Fatima Hasan said:

Homework Statement


How to determine the graph using the properties of a twice-differentiable function ?
View attachment 217909
View attachment 217910

Homework Equations


None

The Attempt at a Solution


when x < 2 , y ' > 0 . So, the function is increasing on this interval. But , the correct answer is ( D) and the function is decreasing when x < 2.
Could somebody help me to solve this problem ?
Thank you for your help
There must be a typographical error in the question: the first line ##x < 2 \hspace{2em} y'>0, y''<0## should read as ##x < - 2 \hspace{2em} y'>0, y''<0##.

Can you see why the original printed form (with ##x < 2## instead of ##x < -2##) does not make sense?
 
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There is probably a typo in the first line. I think it should be ##x<-2##, because otherwise it would contradict the following conditions. Thus it is increasing left of this point, which excludes A and B. The distinction between C and D is then done by the values at the extremes.
 
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Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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