Math 2280 - Introduction to Differential Equations

• May 12th - Your final grades have now been posted to the university system. Class is done! Thank you all for a great semester, and good luck in all you do. Cheers! -Dylan


• April 26th - The solution set for assignment 13 is now posted below, as are the solutions to the practice final exam. Please remember the final exam is Tuesday, April 30th from 8:00 AM to 10:00 AM in our usual classroom.


• April 23rd - The lecture notes with examples for last Friday's lecture, lecture 42, along with the review lecture, lecture 43, are posted below. Tomorrow will be another review day. Also, please note that the extra credit assignment, assignment 14, is now posted below. We'll be having a review session this Friday, April 26th from 6:30 PM until 8:30 PM in our usual classroom, LCB 215. So, if you have any other questions, please bring them to the review session.


• April 18th - The lecture notes for next Monday's lecture, lecture 43, are posted below, along with the solutions for assignment 12. Lecture 43 does not cover any new material, but instead is a review of how to solve some problems from chapter 8 and chapter 9. Mostly chapter 8. I think chapter 8 has been giving a lot of you heartburn, so I wanted to spend some extra time reviewing it.


• April 17th - The lecture notes for Friday's lecture, lecture 42, are posted below, along with the lecture notes with examples for today's lecture, lecture 40. Also posted below is assignment 13, which will be due on Wednesday, April 24th. Finally, the practice final exam is posted below. We'll be reviewing the practice final in class next week, and I'll post the solutions on Wednesday, April 24th. Happy studying!


• April 16th - The lecture notes for tomorrow's lecture, lecture 41, are posted below, as are the lecture notes with examples for today's lecture, lecture 40. Also, assignment 11 has been graded, and the grades are posted on canvas. I'll hand back the assignment in class tomorrow.


• April 15th - The lecture notes for tomorrow's lecture, lecture 40, are posted below, as are the lecture notes with examples for today's lecture, lecture 39.


• April 14th - The lecture notes with examples for last Friday's lecture, lecture 38, are posted below, as are the lecture notes for tomorrow's lecture, lecture 39. See you tomorrow!


• April 11th - The lecture notes for tomorrow's lecture, lecture 38, are posted below. Also posted are the solutions to assignment 11. See you tomorrow!


• April 10th - Assignments 9 and 10 have now been graded, and the grades are available on canvas. I'll hand both assignments back in class on Friday. Also, my office hours for tomorrow need to be modified. I have to bring my cat in to the vet tomorrow morning, so I'll need to move back my office hour a bit. So, tomorrow, my office hour will be from 9:00 AM to 9:50 AM. Yeah, sorry, I know it's not quite a full hour.


• April 9th - The lecture notes for tomorrow's lecture, lecture 37, are now posted below, along with the lecture notes with examples for today's lecture, lecture 36. Also, please note there's a typo on assignment 11. On problem 8.1.25, the Fibonacci problem, the initial conditions should be y(0) = 0, y'(0) = 1. NOT y(0) = 0, y(1) = 1. This typo appears in the book. It has been corrected in the assignment .pdf. Don't worry, the problem will not be graded. Also, exam 4 has been graded, and the grades are posted on canvas. The maximum possible score on the exam was 90 (not 100). The average score was 77.83, the median score was 81, and the standard deviation was 12.71. So, in general, well done! Much better than last time. I'll be handing the exam back in class tomorrow.


• April 8th - The lecture notes for tomorrow's lecture, lecture 36, are now posted below. Also, the lecture notes with examples for today's lecture, lecture 35, are posted below as well. Note we didn't finish all of lecture 35 today, so we'll be finishing at the start of class tomorrow. See you then! Also, please note that at the top of page 7 of lecture 32 with examples there was a typo. What should have said x^{n+2} said x^{n} instead. This has now been corrected. Thanks to Tim Winchester for pointing that out!


• April 7th - The lecture notes for tomorrow's lecture, lecture 35, are now posted below. Exam 4 is mostly graded, and the grades are looking much better than last time. I won't be posting the exam solutions, or handing back exams, until Wednesday. See you tomorrow!


• April 4th - Many new things are posted today. First, the solutions to the practice exam are posted below. Next, the solutions to assignment 10, as well as the new assignment 11, are now posted below. Assignment 11 will be due next Wednesday, April 10th. Finally, the lecture notes with examples for lecture 34 are posted below now as well. Please remember that exam 4 is in class this Friday. I'll be having office hours at the usual time tomorrow morning.


• April 1st - The lecture notes with examples for today's lecture, lecture 33, are posted below, along with the lecture notes for tomorrow's lecture, lecture 34. Also posted below are the solutions to assignment 9. Finally, assignment 8 has been graded, and your grades are available on canvas. I'll hand back assignment 8 in class tomorrow. See you then!


• March 29th - The lecture notes with examples for today's lecture, lecture 32, are now posted below, along with practice exam 4. The solutions for practice exam 4 will be posted on Wednesday, after the review session. Have a good weekend!


• March 28th - The lecture notes for tomorrow's lecture, lecture 32, are now posted below, along with the lecture notes with examples for Wednesday's lecture, lecture 31.


• March 25th - The lecture notes with examples for today's lecture, lecture 30, are now posted below, as are the lecture notes for tomorrow's lecture, lecture 31.


• March 24th - The lecture notes for tomorrow's lecture, lecture 30, are now posted below. Also, the solutions for assignment 8 are posted below. See you tomorrow!


• March 22nd - The lecture notes with examples for lecture 29 are now posted below. Also, there was a typo on problem 7.2.15 for assignment 9. It got mixed up with the last part of problem 7.2.14 from the textbook. The typo has now been corrected. Thank you to Stuart Childs for pointing this out. Have a nice weekend!


• March 21st - Assignments 6 and 7 are now graded, and the grades are posted on canvas. I'll hand back the assignments in class tomorrow. See you then.


• March 20th - Please note the new headline announcements section above. These are announcements that are not tied to a particular class day, but may be of interest to students in the class. As for today's announcements, the lecture notes for today's lecture, lecture 28, are posted below with examples, and the lecture notes for Friday's lecture, lecture 29, are now posted below. I'll be having my usual Thursday morning office hours tomorrow morning, so I'll see some of you then.


• March 19th - Today lecture, lecture 27, is posted below with examples. Tomorrow's lecture, lecture 28, is also posted below. Assignment 8 was due in class today, and solutions will be posted on Thursday. Assignment 9 is now posted below. It is due on Tuesday, March 26th. Please also note that yesterday I posted on this website and said in an email that the median score on the exam was 17.78. Now, the exam went badly, but not THAT badly. The standard deviation was 17.78, while the median was 57.5. Sorry about that. See you tomorrow!


• March 18th - Today's lecture, lecture 26, is posted below with examples. Tomorrow's lecture, lecture 27, is also posted below. Exam 3 has been graded, and the grades are now posted on canvas. The exams were handed back in class this morning. I'm not going to lie, most scores weren't that good. Please remember you get to drop your lowest exam score, and if you do better on the final than on your second lowest exam, your second lowest exam score is replaced with your final exam score. The average for exam 3 was 59.13, the median was 57.5, and the standard deviation was 17.78. On the solutions for exam 3 originally posted here there was an error in problem 6. This has been fixed, and the correct solution is now posted below. Please remember assignment 8 is due in class tomorrow. See you then!


• March 11th - Exam 3 is now posted below, along with the solutions. Also, there was an error on the first page of the homework. The problems enumerated for section 5.4 were not the assigned problems. This was not an error with the rest of the assignment, just the first page. The error has now been corrected. Thank you to Taylor Dunn for pointing this out! Also, the grader told me he'd have assignments 6 and 7 graded and returned to me early next week, and I'll have exam 3 graded soon. Hope everybody is having a good spring break!


• March 8th - We had our third exam today. They'll be graded over spring break. I'll send out an announcement when the grades are posted. The solutions will be posted on Monday evening. Also, assignment 8 is posted below. It will be due on Tuesday, March 19th. Finally, the solutions for assignment 7 are now posted below. Have a great spring break!


• March 6th - Today we finished lecture 25, and had a review session. Lecture 25 with examples is posted below. Also posted below are the solutions to the third practice exam. Please remember that assignment 7 is due on Friday, and our third exam will be on Friday during class. The exam will cover sections 3.7, 3.8, 4.1, 4.2, 5.1, 5.2, 5.4, 5.5, and 5.6 from the textbook. I'll be having my office hour tomorrow morning at the usual time. See some of you then!


• March 5th - The grades for assignment 5 are now posted on canvas. Tomorrow we'll finish lecture 25, and then review for the exam on Friday. See you then!


• March 4th - The lecture notes for tomorrow's lecture, lecture 25, are now posted below. Also, the lecture notes with examples for today's lecture, lecture 24, are posted below as well, along with the solutions to assignment 6. I will be having extra office hours tomorrow from 2:00 PM until 3:00 PM. Starting the first week back from spring break I'll be having two office hours each week, one on Monday from 2:00 PM to 3:00 PM, and the other being the Thursday morning hour I've had all semester. See you tomorrow!


• February 28th - The lecture notes for next Monday's lecture, lecture 24, are now posted below. Also, assignment 7 is now posted below. It is due on Friday, March 8th, the day of our third exam. Please remember that assignment 6 is due in class tomorrow. See you then!


• February 27th - The lecture notes for Friday's lecture, lecture 23, are now posted below. Also, the lecture notes with examples for lectures 21 and 22 are now posted below. Also posted below are the solutions to assignment 5. Please remember that assignment 6 is due on Friday. Also, the window of opportunity to fill out a mid-term evaluation is now shut. Thank you to everybody who did so. I'll be having office hours as the usual time tomorrow morning.


• February 25th - The lecture notes for Wednesday's lecture, lecture 22, are now posted below. Also, the lecture notes with examples for today's lecture, lecture 20, are also posted below. Assignment 4 has been graded, and the grades are posted on canvas. I'll hand back assignment 4 in class tomorrow. Also, tomorrow's lecture will be taped. So, if you're wondering about the camera in the back of the room, that's what's going on. Wear something nice. ;) Also, please note that there was a typo on the assignment 6 homework sheet. On problem 3.7.5 it gave the voltage from the voltage source as 100e^(-10t). The correct value from the textbook is 100e^(-10t)cos(60t). This has now been corrected in the assignment handout below. Thank you to Brad Bowles for pointing this out to me.


• February 24th - The lecture notes for Tuesday's lecture, lecture 21, are now posted below. Last day for the midterm course evaluations! See you tomorrow.


• February 22nd - The lecture notes for lecture 18 are now posted, along with the lecture notes with examples for lectures 18 and 19. The lecture notes for next Monday's lecture, lecture 20, are now posted as well. Finally, please note that the midterm course evaluation is now going on. Please fill out an evaluation form. There's a link above. Have a good weekend!


• February 21st - The lecture notes for tomorrow's lecture, lecture 19, are now posted below, along with the lecture notes with examples for lecture 17. Lecture 18 is not yet posted, but will be posted soon. See you tomorrow.


• February 20th - Assignment 6 is now posted below. Sorry it's late. I want to make sure there's an office hour before it's due, and tomorrow just doesn't seem fair, so it won't be due until next Friday, March 1st. I will, still, be having my office hour tomorrow.


• February 18th - Exam 2 is now graded, and the grades are posted on canvas. I'll hand them back in class tomorrow. The exam was out of 100 possible points. The average score was 84.17, the median score was 86, with a standard deviation of 14.68. There were 9(!) perfect scores. So, all in all, good job, guys! The exam, and its solutions, are now posted below. Also, tomorrow's lecture, lecture 17, is also posted below. See you all tomorrow!


• February 13th - Today was our review session for exam 2. Please keep in mind that exam 2 will be this Friday in class. It will cover sections 2.1 through 2.4 and sections 3.1 through 3.6 from the textbook. I've posted the solutions to the second practice exam, and the solutions to assignment 4, below. Also, the lecture notes with examples for lectures 15 and 16 are now posted below. Please note that on assignment 4 the instructions for problem 3.2.10 were incorrect. The instructions told you to prove that the functions were linearly dependent, when in fact they were linearly independent, and you should have used the Wronskian to figure this out. This is corrected on the assignment 4 that is now posted below, as well as on the solutions. That will definitely not be a problem that is graded. Also, on page 4 of lecture 16 there was a typo. The formula for beats had two sine functions, when there should have been a sine function and a cosine function. This has now been corrected. I'll be having office hours during my usual time tomorrow if anybody wants to come by and talk to me before the exam. Happy studying!


• February 12th - Assignment 3 has been graded, and your grades are now posted on canvas. I'll be handing assignment 3 back in class tomorrow. Also, assignment 5 is now posted below. It will be due on Tuesday, February 19th. Tomorrow in class we will have a review for the second exam, which will be in class this Friday. Please note there was a typo in the originally posted practice exam 2. It said the polynomial x^4 + 2x^3 + x - 12x + 8 has x = 1 as a root of multiplicity 2. It should have said the polynomial x^4 + 2x^3 + x^2 - 12x + 8 has x = 1 as a root of multiplicity 2. This has now been corrected in the practice exam posted below. Thank you to James Longaker for pointing out the typo. See you tomorrow morning!


• February 10th - The lecture notes for tomorrow's lecture, lecture 15, are now posted below, as are the lecture notes with examples for last Friday's lecture, lecture 14.


• February 8th - Assignment 2 has been graded, and the grades have been posted on canvas. The assignment will be handed back in class on Monday. Also, the solutions for assignment 3 are now posted below. Finally, please note that our second exam will be on Friday of next week. It will cover sections 2.1 through 2.4 and 3.1 through 3.6. A practice exam is posted below. The solutions to the practice exam will be posted on Wednesday of next week. Have a good weekend!


• February 7th - The lectures notes with examples for lectures 12 and 13 are now posted below, along with the lecture notes for tomorrow's lecture, lecture 14.


• February 4th - The lecture notes with examples for lecture 11 are now posted below, along with the lecture notes for tomorrow's lecture, lecture 12. Also, it's now been pointed out to me what I did wrong on exercise 26 of section 2.3, which was an example problem in lecture 9. The problem gives the diameter of the asteroid, but the radius of the earth. I thought they were both radii. Thank you to Sarah Sandoval for pointing out the error! Also, assignment 4 is now posted below. It is due a week from today on Monday, February 11th. Please remember that assignment 3 is due in class tomorrow, February 5th. See you tomorrow morning!


• February 3rd - The lecture notes for lecture 11, tomorrow's lecture, are now posted below, along with the lectures notes with examples for lectures 8, 9, and 10. Please note that in my lecture last Friday (lecture 10) I made a silly arithmetic mistake on the h=.25 example. This has been corrected in the lecture notes for lecture 10 posted below. Also, on lecture 9 the final example is taken from exercise 26 of section 2.3 from the book. The way I calculate it you're stranded, but the back of the book says you're not. This means either: a) I've made a stupid mistake. b) The book makes an assumption I'm not making. c) The back of the book is wrong. Any of these are possible. If you can figure out which one it is and let me know I'd be very interested, and would even give you some extra credit. See you tomorrow morning!


• January 31st - The lecture notes for lecture 10 are now posted below, along with exam 1 and its solutions, and the solutions for assignment 2. The first exam has now been graded, and grades have been posted on canvas. I'll hand back the exam in class tomorrow. The exam was out of 100 possible points. The mean score was 74.36, with a standard deviation of 17.86 and a median of 78.5.


• January 29th - The lecture notes for lecture 9 are now posted below, along with assignment 3. My goal is to have exam 1 graded, and the grades posted online, before I go to bed tonight. I'll send out an email letting you know if I achieve that goal.


• January 23rd - The lecture notes, with examples, for the first seven lectures are posted below. This covers all the material up through chapter 1. Also, the solutions to the practice exam are posted below. I'll have office hours tomorrow at the usual time, and the first exam will be on Friday. It covers chapter 1 (sections 1.1 through 1.6) of the textbook.


• January 20th - The first exam will be next Friday, and a practice exam is now posted below. The solutions to the practice exam will be posted on Wednesday, January 23rd. Also posted below are the solutions to assignment 1. Finally, I've posted the exams, along with solutions, from the previous two times I've taught this course. They won't replace the practice exams, but they might be a useful study resource, so I've made them available.


• January 14th - The notes for lecture 6 are now posted below, as are the notes with examples for lectures 3, 4, and 5. Also, assignment 2 is posted below. It's due on Tuesday, January 22nd because we have Monday off. Assignment 2 is a long and somewhat difficult assignment, so I'd recommend getting started on it as soon as you can.


• January 10th - The lectures notes for lecture 4 and lecture 5 are now posted below.


• January 8th - The lecture notes for lecture 3 are now posted below, along with the lecture notes with examples for lecture 2. There was a typo in the .pdf for assignment 1. On problem 1.20 it said y' - x - y, where it should have said y' = x-y. This has been corrected, and the .pdf file linked to below does not contain the typo, but if you printed out the .pdf before tonight please take note of the typo. Thank you to Steven Farr and Michael Bradshaw for alerting me to the typo. See you all tomorrow morning!


• January 7th - The lecture notes for lecture 2 are now posted below, along with the lecture notes with examples for lecture 1. Assignment 1 is also posted below. There is a .pdf with all the problems for assignment 1. If you'd like, you can print out the .pdf and use it to do assignment 1. Also, I've decided not to do "recommended problems". The assigned problems should be sufficient.


• January 6th - Our first class is tomorrow morning at the very early hour of 8:35 AM. The website for the class is (obviously) now up, and the syllabus and schedule are posted below. See you tomorrow!

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