Turn in #5 is due Thursday, Oct. 29, 2015!
This is for discussing assignments from WEEK 7-8, including homework,
turn-in #5, Midterm Exam review, in-class
work or lessons, or anything else related to the
class from these weeks. Please be sure to include your
name at the end of your post for credit. When answering a question, DO
NOT GIVE SOLUTIONS! Provide hints or explain a method that you used, but
do not give the final result. As always, RESPECT IS A MUST! Anyone
abusing this forum will be banned from future use (meaning, no extra
credit!!!).
Is there a way in problem number 2 on the turn in, that I can find the concavity of the function with out drawing/finding the second derivative?
ReplyDeleteNo, you need the second derivative. Your calculator can graph this for you, remember...
DeleteCan we use our calculators for #2 then, even though it's a non-calculator problem? -Claire Westerlund
DeleteI thought we were talking about the ice cream question. My mistake. I do not have the turn in here with me, so I am trying to go from memory. Is question 2 the graph of f'? In any case, you need to consider the sign of f" to determine concavity, which can be obtained from a graph of f'
DeleteFor 2a, can an endpoint be a relative minimum? -Claire Westerlund
ReplyDeleteNo, an endpoint can only be an absolute extrema.
DeleteFor book work number 20 on the turn-it, what equations am I looking for to derive? I don't understand why Jane shouldn't just row to the nearest point of the shore and walk the rest of the way.
ReplyDelete-James Gruich
This is similar to number 8 on the class examples from today. The path you describe is not optimal because it is longer distance and so will take longer. Keep in mind that distance = rate * time for this problem.
DeleteJane doesn't just row 2 miles & then walks 6 miles because there are varying speeds from walking to rowing so it's more efficient to specialize on walking over rowing at certain points and vice versa. To solve this you have to find the distance Jane is rowing and then walking in terms of x; A good way to do this is to split the total distance of the shorewalk into x & 6-x. You then express this in total time it takes her to row & walk and then take derivative & see where the y value of the derivative is 0. From then you get relative lengths to see where Jane should row to, ect.
Deleteyeet
-Daniel Soares
For problem 2, should (2,2) be included as a point of inflection because f' changes from increasing to decreasing or would it not be included because there's no concavity at that point?
ReplyDeleteA point of inflection is a point where f changes concavity, f' changes directions, and f" changes signs.
DeleteIf f'' never changes signs, then can concavity be found from f''?
ReplyDelete-Sarah Mostofizadeh
How do you justify that a point is an absolute extrema without using the graph?
ReplyDeleteHope Lamphere
You would take the derivative of the equation and find the critical points. You would then evaluate the function at the critical points and the endpoints. The absolute extrema will be the highest and lowest points on the graph and can only occur at the critical points and/or endpoints on an interval. From there you would take the highest and lowest as the absolute minimum and maximum respectively.
DeleteFor number 1 if my equation for volume has two unknowns, the circle radius and the angle, how do I get it to have just the angle as the unknown?
ReplyDelete-Cara Young
Yes, you will. Keep in mind that the radius is fixed based upon the size of the circle, so you can choose an arbitrary value for it, say r=1 (hint).
DeleteThis comment has been removed by the author.
ReplyDeleteHey guys! I heard that the midterm is 60% of our class grade... is this true?
ReplyDelete20%. See the syllabus posted online for further grade-related details.
DeleteFor finding Points of Inflection, do we just find the zero's of the second derivative? If not, can you please explain how to properly find the POI's? -Claire Westerlund
ReplyDeleteYeah. POIs are the zeros of the second derivative because that's the only place where the double prime can switch sides (or switch concavity).
Delete-Rachel F
Once you find the zeros of the second derivative you also have to make sure the sign changes. If it does then it is a POI.
Delete-Sarah Mostofizadeh
For the midterm will there be diagrams for the story problems?
ReplyDelete-Rachel F
Do extremas include local and global max and mins?
ReplyDelete-Sarah Mostofizadeh