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Welcome to Math 20D

Instructor Lecture Time (MWF) Location
Adam Bowers B 2:00 - 2:50 P.M. PETER 108

TED:   Check your grades.
WileyPLUS:   Online homework system.
MATLAB:   Lab information/assignments.

Instructor office hours: (click here)

Contacting me:   If you want to ask me a question about the course, use our Math 20D Piazza webpage.


Mar 19

Pre-Final Exam Scores Posted

All scores except for the final exam have been posted to Ted. The final exam scores will be posted when the exams are graded. (I do not know when that will be.) Make sure that the scores say what you expect them to say. If any of the currently posted scores are in error, they must be changed before the final grades are posted. (Final grades will be posted sometime before next Tuesday.)

Mar 13

CAPE Response Rate Success

Hooray! You have achieved a 73% CAPE response rate, so the surveys in TED are now worth 10 points!

Mar 13

Matlab Scores

All Matlab assignment scores have been posted to TED.

Mar 12

Final Week Announcements

Don't forget to take your Matlab Quiz on Thursday! (Or on Wednesday, if you scheduled an optional time.)

Final Exam Information
• Our Final Exam will be held in the REC GYM. (See the class "Exams" page for more information.)
• There is a list of exam topics on the class "Exams" page.
• I guarantee we will check IDs during the final exam. Make sure you bring a photo ID.
• Please, please remember to bring a Blue Book. Two might be nice.
• Putting your discussion section number on your Blue Book is worth ONE POINT.
See the first question on the final exam here.

Solutions on Piazza
• Solutions to the Spring 2009 Midterm 2:
• Solutions to the Spring 2009 Final Exam:
• All solutions will be removed from Piazza after the final exam has been taken.

CAPE Response Rate
The CAPE response rate is currently at 54%. If you want the Ted opinion surveys to count for 10 homework points, you must get it up to 70% by the end of the week. (If you get the response rate to 80%, the Ted opinion surveys will be worth 14 points.)

Mar 8

Solution to 5.2 Exercise #8

I have posted my handwritten solution to 5.2 Exercise #8.  This exercise was not a homework problem, but it demonstrates the difficulty of finding the general solution to a differential equation in series form about a point other than zero.

Mar 8

Solutions to Starred Exercises for Chapters 7 & 5

Solutions to the starred exercises in 7.5-7.8 have been posted to Piazza here:

Solutions to the Chapter 5 starred exercises have been posted to Piazza here:

Mar 2

TED Opinion Surveys

I have posted two anonymous opinion surveys to TED. One survey is about your experiences with online homework (9 questions) and the other is about your textbook (5 questions). These are anonymous opinion surveys, but they are also homework assignments. Each survey is worth 1 point. They are graded only on completion. If TED says you completed the survey, then you get full credit.

At the moment, each survey is worth 1 point, but if we get a good CAPE response rate (evaluations start Monday, Mar 4), then I will increase the point values:

CAPE = 70%: Homework Survey will be worth 9 points
CAPE = 80%: Textbook Survey will be worth 5 points

Yay points!

Feb 28

Final Exam Information

Our Final Exam will be held in the REC GYM. Check the class  "Exams"  page for more information.

Also: Question Zero on the Final Exam will ask for your discussion section number and exam version. Failure to clearly indicate both items will result in the loss of a point!  You can even see the first question of the final exam here.

Feb 27


Don't forget that you have a MATLAB quiz this quarter. The best way to prepare for the MATLAB quiz is by working carefully through all the labs.

Also: Remember, any time you are asked to draw a phase plane, you can use MATLAB. Or use this nifty online tool.

Feb 21

Solution to 7.4 Exercise #6

I have posted my handwritten solution to 7.4 Exercise #6.  In class, I indicated how to solve the problem, but did not work out an example.  (There are other ways to do this exercise.)

Feb 21

Solutions to Chapter 7 Starred Exercises

Solutions to the Chapter 7 starred exercises have been posted to Piazza here

Please be aware that the emphasis of Midterm 2 will be on Chapter 3. While I will certainly ask something from Chapter 7, it will have more to do with differential equations and less to do with linear algebra and matrix operations.

Also, please be aware that the old Miderm 2 on the Exams page covers only material from sections 7.5-7.9, none of which will be on our Midterm 2. (That is why I am not posting solutions for it.)

Feb 15

Drop In Office Hours for Exam Week

Additional DROP IN (i.e., no appointment necessary) hours for exam week!

  • Math 20D:   Thursday, Feb 21:   2 - 4 P.M.

Feb 12

Midterm Exam 2

All students will take the exam in PETER 108, our usual lecture hall.
Check the class Exam Information if you have any questions.

Feb 11

Solution to 3.5 Exercise #8

I want everyone to be able to see all of the details of how to work out a multipart problem using the Method of Undetermined Coefficients. Consequently, I have posted my handwritten solution to 3.5 Exercise #8. In class, I did not give you the best way to label the coefficients. Notice in this exercise how we assign the coefficients for Y2. This way we can be sure all of the coefficients are independent of the others.

Jan 27

Homework 4 Due Date Change

The due date for Homework 4 has been changed to Monday, Feb 4.
(Please see the Homework page.)

Jan 25


Solutions to the starred homework exercises, as well as the old midterm, can be found on Piazza here:

Jan 24

Exam Locations

Not all exams are taken in the usual lecture hall!
Check the class Exam Information page to find your exam location!

Jan 23

Homework 3 Due Date Change

The due date for Homework 3 has been changed to Monday, Jan 28.
(Please see the Homework page.)

Jan 16

Discussion Section Room Changes

Those discussion sections that had been meeting in APM 2301 (B01-B06) will now be meeting in MANDE B-152 (in the first basement level of Mandeville Hall). Please note that Mandeville has two basement levels.

Jan 14

Where to go with WileyPlus questions

Jan 13

Office Hours

My office hours are now posted:

Please note that (due to overwhelming demand) all office hours are to be made using a web tool at the above URL.
If a time is not listed as available, then I am already booked for that time.

Jan 3

Registering for WileyPlus

You can register for the class on WileyPlus here:

Just click on "Create Account" and accept the License Agreement. Enter your registration code on the page that appears after you press "Continue". Also, if you do not yet have a WileyPlus code, you can purchase a code without buying a physical copy of the book. Just follow the above directions and then click on "Buy Course Access". It isn't cheap, but it comes with electronic access to the book.

Registration instructions: Wiley Plus Flyer

Make sure you register using your UCSD email address. Otherwise you may not be given credit for your homework.

Jan 2

Make sure you buy the right textbook!

The textbook used in this course is Elementary Differential Equations (9th Edition), by Boyce and DiPrima. You must buy a copy of the book that has the  WileyPLUS Online Homework code.  Otherwise you will have to buy the code separately!

You may buy the textbook from the bookstore in a  LOOSE LEAF BINDER READY  version. Do not buy the hardback version at the bookstore because it will not have the access code for the homework.

If you want  ELECTRONIC ACCESS ONLY,  you can buy the WileyPLUS code separately.