Differential Equations - Fall 2025 (DRAFT)
Euler portrait
Leonhard Euler, 1707-1783
Laplace portrait
Pierre-Simon Laplace, 1749-1827
Cauchy portrait
Augustin Louis Cauchy, 1789-1857
Click on the photos to be taken to a biography presented by the MacTutor History of Mathematics website (accessed 3/20/2025).

COURSE NUMBER: MATH 2120
TIME: 1:20-2:40 TR; PLACE: Gilbreath 104
INSTRUCTOR: Robert "Dr. Bob" Gardner; OFFICE: Room 308F of Gilbreath Hall
OFFICE HOURS: 4:15-4:45 TR and by appointment; PHONE: 439-6979 (Math Office 439-4349)

E-MAIL: gardnerr@etsu.edu
WEBPAGE: Dr. Bob's faculty webpage (see my webpage for a copy of this course syllabus, copies of the classnotes in PDF, and updates for the course).

TEXT: Introduction to Ordinary Differential Equations, 4th Edition by Shepley L. Ross (John Wiley and Sons, 1989).

Ross' Introduction to Ordinary Differential Equations book, 4th edition

SUPPLEMENTAL REFERENCES: For justification of several claims made in class, we will appeal to Shepley Ross' Differential Equations, 3rd Edition (John Wiley and Sons, 1984). This is not our textbook, but it includes all of the material of our textbook along with several additional chapters. The attraction for your instructor to Ross' Introduction to Ordinary Differential Equations is the availability of this strong supplemental reference. In addition, we will turn occasionally to Kenneth Howell's Ordinary Differential Equations: An Introduction to the Fundamentals, 2nd edition (CRC Press, 2019) for justification of results. A third supplemental reference is George Simmons' Differential Equations with Applications and Historical Notes, 3rd edition (CRC Press, 2023). We have some supplemental notes on applications based on this source.

Ross' Differential Equations book, 3rd edition Howell's Ordinary Differential Equations book, 2nd edition Simmons' Differential Equations with Applications book, 3rd edition

COURSE DESCRIPTION: The 2024-25 ETSU Undergraduate Catalog describes this course as: "Offers first order differential equations and applications; second and higher order linear differential equations and applications; Laplace transforms; and systems of differential equations." These topics are covered in Chapters 1, 2, 3, 4, 5, 7, and 9. This is ambitious! In practice, we will likely cover Laplace transforms (Chapter 9) briefly and not have time to consider systems of linear differential equations (Chapter 7). We should cover series solutions (Chapter 6), though.

PREREQUISITE: The catalog states that the prerequisite is a C (2.0) or better in MATH 1920 [Calculus 2]. It is recommended but not required that students take MATH 2010 [Linear Algebra] before taking MATH 2120 [Differential Equations].

DESIRE2LEARN: I will not rely on the Desire2Learn ("D2L") website for the posting of notes and supplements; all of this material is freely available on my faculty webpage and does not require a login. I will use D2L to collect homework (in DropBox) and to post your grades, homework solutions, and recordings of class lectures.

CLASS NOTES: We will use projected digital notes for the presentation of definitions, examples, and proofs of some theorems. Copies of the notes are online. It is recommended that you get printed copies of the notes before the material is covered in class. This will save you from writing down most notes in class and you can concentrate on listening and supplementing the notes and examples with comments which you find relevant. You should read the online notes to be covered in class before each class (we will not have class time to cover everything in the notes; they are very thorough). Try to understand the examples and the meanings of the definitions. You should also read each relevant section of the book, paying particular attention to examples.

ABOUT THE COURSE:

OUTLINE: Our tentative outline is:
Chapter 1. Differential Equations and Their Solutions:
Chapter 2. First-Order Equations for Which Exact Solutions Are Obtainable:
Chapter 3. Applications of First-Order Equations:
Chapter 4. Explicit Methods of Solving Higher-Order Linear Differential Equations:
Chapter 5. Applications of Second-Order Linear Differential Equations with Constant Coefficients:
Chapter 6. Series Solutions of Linear Equations:
Chapter 9. The Laplace Transform:

GRADING: Your grade will be determined by the average on four tests T1, T2, T3, T4. The test will be spaces at 3 or 4 week intervals and the fourth test will be given during finals week. Your average is determined by:

AVERAGE = (T1 + T2 + T3 + T4)/4,
Grades will be assigned based on a 10 point scale with "plus" and "minus" grades being assigned on a 3 point subscale (for example, a 90, 91, 92 is an A-).

HOMEWORK: Every class, a set of a few homework problems will given. These will not be collected, but any questions on them will be addressed during the following class. It is imperative that you work on these problems!!! This is really how you learn the material, and the tests will be largely based on these problems (or ones very similar to them). These problems can be time consuming, so you don't want you first attempt at working such problems to come during a test! Handwritten solutions to some of the homework problems will be posted on D2L.

ACADEMIC MISCONDUCT: If you have any questions about the assigned homework problems, then I will try to address them in class. If you need additional information, then let me know. We can work it out through e-mail, Zoom, or in-person meetings in my office. I will provide all paper for the tests. You will only need a pencil and eraser. You will put your backpack at the front of the classroom during the test and your phone will be placed on the table at the front of the room (so please make sure you have the phone silenced). Cheating on a test will result in a grade of 0 on that test. These are examples of academic misconduct and I will have to act on this as spelled out on ETSU's "Academic Integrity @ ETSU" webpage (last accessed 8/18/2024). When such a charge is lodged, the dean of the College of ARts and Sciences is contacted. Repeated or flagrant academic misconduct violations can lead to suspension and/or expulsion from the university">Academic Integrity @ ETSU webpage (last accessed 1/16/2025). When such a charge is lodged, the dean of the College of Arts and Sciences is contacted. Repeated or flagrant academic misconduct violations can lead to suspension and/or expulsion from the university.

SUPPLEMENTAL REFERENCES:

SYLLABUS ATTACHMENT: You can find an on-line version of the university's syllabus attachment (which contains general information concerning advisement, honor codes, dropping, etc.; accessed 1/16/2025).

ZOOM AND REMOTE ATTENDANCE: A ZOOM meeting is set up for each lecture through D2L. I encourage you to attend the in-person lectures if possible, but if you need to attend though ZOOM then that is fine. In particular, if you are not feeling well the please do not attend class in person. You can ask questions through D2L and I will respond, just like in class. These ZOOM meetings will be recorded and posted on D2L.

CAMPUS SAFETY: East Tennessee State University is dedicated to creating a safe and healthy environment for all students, faculty, staff, and visitors by fostering a strong culture of safety that extends beyond compliance with regulations. All members of the ETSU community play a crucial role in this shared responsibility. You are encouraged to report any issue without fear, ensuring a supportive environment. As Buccaneers, make safety a priority and contribute to a positive, productive campus community by:

Emergency Management - Faculty Emergency Guide/Emergency Training/Campus Emergency Plan/Building Safety
ETSU Police - Reporting Crimes, Assaults/Cleary Act/Reports and Information
Safe Voyage Shuttle/Escort - Student Safety Services
(These websites were accessed 1/19/2025.)

IMPORTANT DATES: (see the official ETSU calendar for more details; accessed 1/16/2025):


Return to Dr. Bob's webpage

Last updated: March 31, 2025.