Wednesday, January 7, 2015

Term 2, Week 4-6 Disucssion (1/5 - 1/23)

Turn in #12 is due Tuesday, Jan. 20, 2015!

This is for discussing assignments from WEEK 4-6, including homework, turn-in #12, the Midterm Exam, and 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.  Since this board covers multiple weeks, there is a 2 point maximum for bonus, but you most post multiple times to earn both points. 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!!!).

42 comments:

  1. When using Euler's method will we always be given delta x?

    Thanks,
    Rachel Hersch

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    Replies
    1. You will be given delta x or be told to split the interval into n equal parts, which allows you to compute delta x.

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  2. I have altered the calendar for January slightly (updated version is now on course website). Things of note: Turn in #12 will be due Tues 1/20 now instead of next Thurs., and our Midterm Exam will be Thurs and Fri 1/22 & 1/23.

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  3. Will Euler's method usually show up on the calculator or non calculator section of the AP? And will we be able to use a calculator for it on quizzes and tests?

    -Amanda Bachand

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    Replies
    1. Since 1999 it is most frequently part of the free response, non calculator section. Typically as part of a question dealing with a differential equation, which will inevitably ask at some point to separate variables to find a particular solution. Usually you are only asked for 2-4 steps using Euler's method.

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  4. On the AP, will there be a question asking for the improved euler's method? Thank you,
    Maggie Hammond

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  5. Is the quiz coming up this week calculator or non calculator?

    Thanks!
    Laura Goo

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    Replies
    1. It is not yet written. Be prepared for either case.

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  6. I am a little confused on number 24 on the homework. When a problem asks to tell if the integral diverges, should I simplify the whole integral before I change the end points of the integral and then take the limit or do I change the end points before simplifying and take the limit right away?

    Thanks,
    Emma Gijsbers

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    Replies
    1. You must find the limit as the limit of integration approaches infinity. If this limit is finite, then the integral is equal to this value. If the limit is infinite (does not exist) then the integral diverges.

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  7. For question 50 part B on page 443, are we allowed to just plug that into our calculator? Or do we have to be able to evaluate the integrals by hand?

    Thanks,
    Katie Weitzel

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    Replies
    1. Sorry, I must have missed this question the other day. I don't have the text with me, so please ask me in person and we'll figure it out.

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  8. On the turn-in is number 5 suppose to be a calculator problem?

    Thanks,
    Rachel Hersch

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    Replies
    1. #5 is a non-calculator problem. Notice in part b you do not have to evaluate the integral.

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    2. Do we have to find the intersection points for 5b on the turn in because the function doesn't factor?

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    3. Since it is a non-calculator problem and the intersections are not able to be found algebraically, I would label the x-coordinates of those points as "a" and "b" and then use those in my integral.

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    4. how would you evaluate part c?
      Marie Suehrer

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    5. Distribute the polynomials and integrate term by term. Some terms will require IBP. This problem is good practice on brushing up on anti derivatives for the midterm.

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    6. Ok, I started doing it that way but didn't know if it was all necessary,
      Thanks,
      Marie

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    7. sorry for the many posts, but since its turns into all fractions, is it okay if we leave it in terms of several fractions?
      Marie

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    8. Remember, once you have plugged in he values into the anti derivative you can stop.

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  9. Will accumulation using FTC (7.1) problems be on Friday's quiz?
    Thanks,
    Jenna Weed

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    Replies
    1. It is not a primary emphasis, but ANY topic we have covered is always "fair game". The primary focus is differential equations including approximation with Euler's and improper integrals.

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  10. Will we need to memorize the logistic growth equation for tomorrow?
    Thanks,
    Allison Honet

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  11. Will the solutions be posted for the midterm review?
    Thanks!
    Lexi Kizy

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    Replies
    1. If I get time to make a key, I will post it. My priority right now is grading the quizzes so that you can have those back as study aides.

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  12. How would you go about integrating 5c on the turn-in?

    Thank you,
    Angela Satullo

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    Replies
    1. See above, I just answered this question 😃

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  13. For 1B of the turn in, do we have to show any work for how we got to the integral expression?

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    Replies
    1. Sorry, I am just now seeing this. Whenever a problem asks for you to set up an integral, you do not need supporting work.

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  14. Do we need to have the power reducing formulas memorized for the midterm?

    -Amanda Bachand

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    Replies
    1. Short answer, no. They are very useful, however, and worth committing to memory when you will be doing lots of integrals involving trig functions.

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    2. By the way, the double angle and power reducing identities are the same! So, if you remember one, you have both.

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  15. Hey Mr. Wilson,
    Were you able to create an answer sheet for the review?

    - Rafey

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    Replies
    1. No, I will not have time to make one. Post specific questions here or see me in the AM.

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  16. Rotational volumes will not be on the midterm, correct?
    -Kai Selwa

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    Replies
    1. Correct. Volumes of solids of revolution will not be on the midterm. Volumes of solids with known cross sections WILL be, though.

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  17. For number 7d on the midterm review and questions like it on the midterm or future exams, after we solve it and get it down to the integration by parts equation, can we stop after xe^(-x^3) to show that it diverges or will more points be based off the rest of the problem with solving the rest of the integral?

    Thanks,
    Emma Gijsbers

    ReplyDelete
    Replies
    1. Well, once you've achieved a place in your work where you've shown a divergent limit, then you can stop. The integral you have, however, converges. You currently have an indeterminate form, so use L'Hopital's.

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  18. What's the difference between using the cross-sectional area formula that has a pi vs finding the area of a cross-section and multiplying by dx? Is the first one just used to find rotational area?

    Rafey R

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    Replies
    1. I'm not sure I understand your question. The only time you have Pi in your area formula is if the cross sections are circular, which always results when revolving a region about an axis.

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