Turning points (maximum/minimum) question review.

[pedromartins]

Hi guys,

I'm currently reviewing a question bank and have come across some questions I personally think are not the best. These questions are targeted at students aged around 15 and are an introduction to differentiation.



Thanks in advance for the help.

 

[JeffM]

Why do you think they are not the "best"?

 

[pedromartins]

From my interpretation of the questions, the answers are incorrect.

For the first figure, going from right to left on a graph, having a positive gradient, then a gradient equal to zero and then positive again, doesn't correspond to a minimum.
A minimum would require, from right to left, the gradients to be positive, zero and negative.
Assuming right to left on the graph is moving from positive direction of x axis to negative direction of x axis.

 

[Dr.Peterson]

Hi guys,

I'm currently reviewing a question bank and have come across some questions I personally think are not the best. These questions are targeted at students aged around 15 and are an introduction to differentiation.

View attachment 28543View attachment 28544

Thanks in advance for the help.

I had to look closely to realize that answers are given. I presume your concern is that the answers are wrong. If so, you are correct.

These aren't turning points at all. They're points of inflection

A poll is not the way to get a useful answer to this sort of question, since what's really needed is discussion; but the fact that you asked, in the poll only, about the questions being "incorrect", was what made me look closely. (I really dislike unreadable color schemes.)

 

[pedromartins]

I had to look closely to realize that answers are given. I presume your concern is that the answers are wrong. If so, you are correct.

These aren't turning points at all. They're points of inflection

A poll is not the way to get a useful answer to this sort of question, since what's really needed is discussion; but the fact that you asked, in the poll only, about the questions being "incorrect", was what made me look closely. (I really dislike unreadable color schemes.)

Thank you for the reply. I got a bit carried away with the poll since I've never posted here.