Math 285
Differential Equations


Spring 2011 Course Information

Instructor Martin Frankland
Office 238 Illini Hall
Lectures Section G1: MWF 3:00-3:50 PM in 245 Altgeld.
Section X1: MWF 12:00-12:50 PM in 245 Altgeld.
Office hours MW 4:10-5:00 PM, primarily for administrative questions. For math questions, first go to tutoring.
TutoringMonday through Thursday, 7-9 PM, details here.
Textbook C. H. Edwards and D. E. Penney, Differential Equations and Boundary Value Problems, fourth edition.
Grading The course grade is calculated as follows.
Final exam: 40%
Midterms: 40% (20% each)
Homework: 20%
Important dates Wednesday January 19: First lecture.
Friday February 25: Midterm 1, in class.
Friday March 11: Drop date.
March 21-25: Spring break. No lectures.
Friday April 15: Midterm 2, in class.
Wednesday May 4: Last lecture.
Wednesday May 11: Final exam for section X1, 7-10 PM, in 245 Altgeld.
Thursday May 12: Final exam for section G1, 1:30-4:30 PM, in 245 Altgeld.
Homework Homework assigned each week will be posted below on this webpage. It will be due in class on the next Wednesday.
Syllabus Here is the syllabus of the class.
Grades Students registered for the class can view their grades here. You will need your NetID and password.

Announcements

May 23 : Letter grades have been officially entered and will appear some time next week. Please ignore the temporary "NR" that appears on your record.
May 20 : Grades for the final are available online. Letter grades for the course will appear later on the university website, not the math department site linked above. Note that the grades you see online do not take into account the deal described under March 7 below.
May 20 : Here is the curve applied to the final. Let x denote the raw score out of 80. The curved score is...
    0 ≤ x ≤ 10 : 3x
    10 ≤ x ≤ 80 : 30 + 58(x-10)/70
In other words, a line segment from (0,0) to (10,30) and from there to (80,88).
    Average (after curving): 80.7 %
May 20 : Here are solutions to the final, versions X1 and G1.
May 17 : Grading is underway and will be finished on Friday. Thank you for your patience.
May 4 : Please bring your student ID to the final exam. You cannot take the exam without it.
May 4 : Here is a review sheet for the final, with important information.
May 3 : Here are solutions to the practice final.
May 2 : The review session on Wednesday May 4, 6-7 PM, is in room 165 Everitt Lab (across Green Street from Altgeld).
May 1 : Here is the practice final.
Apr 27 : Here is the curve applied to midterm 2. Let x denote the raw score out of 40. The curved score is...
    0 ≤ x ≤ 8 : 2x
    8 ≤ x ≤ 40 : 16 + 24(x-8)/32
    Average (after curving): 77.7 %
Apr 26 : Here is a grading key for midterm 2.
Apr 14 : Please bring your student ID to the exam tomorrow.
Apr 12 : Here are solutions to the practice midterm.
Apr 9 : Here is the practice midterm 2 as well as a review sheet.
Apr 6 : Here is a solution to problem 3.8 #16.
Apr 5 : Review session on Wednesday April 13, 6-7 PM, room 269 Everitt Lab (across Green Street from Altgeld).
Apr 4 : No lecture on Monday April 11.
Apr 1 : Here is a solution to problem 9.4 #14.
Mar 20 : Here are lecture notes from last Friday's lecture on section 9.2.
Mar 17 : There is class tomorrow (Friday). Someone else will be lecturing instead of me.
Mar 16 : Here is a solution to problem 9.1 #17.
Mar 7 : Policy update regarding the final. If the final is better than the average of the midterms, then the final will be worth 50% of the total score and the lowest midterm 10% instead of 20%.
Mar 4 : Here is the curve applied to Midterm 1. Let x denote the raw score out of 50. The curved score is...
    0 ≤ x ≤ 20 : 1.5 x
    20 ≤ x ≤ 40 : x + 10
    40 ≤ x ≤ 50 : 30 + 0.5 x
    Average (after curving): 77.7 %
Feb 24 : Please bring your student ID to the exam tomorrow.
Feb 22 : Additional review session on Wednesday (tomorrow) 6-7 PM, room 269 Everitt Lab.
Feb 22 : Here are solutions to the practice midterm 1.
Feb 21 : Tuesday office hours (tomorrow) will be 2:30 - 3:50 PM.
Feb 18 : Here is the practice midterm 1.
Feb 18 : Here is a review sheet for midterm 1, with information on the material covered.
Feb 18 : I will not be holding office hours this Monday Feb 21, but on Tuesday Feb 22 instead.
Feb 2 : Lecture canceled due to the snow storm. Turn in homework 2 on Friday Feb 4 in class.

Homework

Show your work. Answers without justification will receive no credit.
No late homework will be accepted.

Week 1 (due Jan 26)
Section 1.1 : 7, 8, 9, 11, 18, 19, 33.
Section 1.2 : 4, 5, 6, 15, 18, 25.

Week 2 (due Feb 4, not Feb 2)
Section 1.3 : 4 (pick a few points; a rough sketch is ok), 11, 13, 14 (warning: incomplete explanation in the book), 15.
Section 1.4 : 2, 13, 14, 17, 19, 21 (explicit means y(x)=...), 24, 34, 45.
Section 1.5 : 2, 5, 9, 18, 22, 34.

Week 3 (due Feb 9)
Section 1.6 : 2, 6, 13, 17, 21, 23.
Wed Feb 2 : Lecture canceled.
Section 2.1 : 10, 11, 21, 28.

Week 4 (due Feb 16)
Section 2.3 : 2, 3, 4, 5, 10, 20. For #10 and #20, feel free to use formulas derived in that section of the book.
Section 3.1 : 2, 17, 27, 28.
Section 3.1 : 33, 39, 21, 24, 25, 29, 31.

Week 5 (due Feb 23)
Section 3.2 : 4, 7, 8, 14, 21.
Section 3.3 : 2, 5, 12, 15, 21.
Section 3.3 : 8, 14, 16, 23, 24.

Week 6
Section 3.4 : 3, 4, 14. (due Mar 9 with HW 7)
Wed Feb 23 : Review session, with practice exam and solutions. Suggested additional problems: Chapter 1 #31, 32, 33.
Fri Feb 25 : Midterm 1.

Week 7 (due Mar 9; includes first lecture of Week 6)
Section 3.4 : 15, 18. (Graphs don't need to be very precise.)
Section 3.5 : 1, 2, 3, 30, 31.
Section 3.5 : 9, 10, 22, 24, 34.

Week 8 (due Mar 16)
Section 3.5 : 47, 48, 53. Use variation of parameters, NOT undetermined coefficients.
Section 3.6 : 2, 19, 20.
Section 3.6 : 8, 12, 17. Warning: Typo in the answer to #12. For #17, feel free to use formula (21) for C(ω).

Week 9 (due Mar 30, after spring break)
Section 9.1 : 3, 6, 27.
Section 9.1 : 13, 15, 20.
Section 9.2 : 1, 6, 12, 15.

Week 10
Spring break. No lectures.

Week 11 (due Apr 6)
Section 9.3 : 2, 11, 15, 16.
Section 9.4 : 1.
Section 9.4 : 10, 13 (ignore the phase angles, only find the amplitudes). For 13, feel free to use formulas derived in that section.

Week 12 (due Apr 13)
Section 3.8 : 1, 2.
Section 3.8 : 15, additional problem.
Section 9.5 : 1, 2, 4.

Week 13 (no homework assigned)
Mon Apr 11 : No lecture.
Wed Apr 13 : Review session with the practice exam and solutions.
Wed Apr 13 : Additional review session, 6-7 PM, 269 Everitt Lab.
Fri Apr 15 : Midterm 2.

Week 14 (due Apr 27)
Section 9.5 : 9, 5, 11, 13.
Section 9.6 : 2, 6.
Section 9.6 : 7, 11, 13, 14.

Week 15 (due May 4)
Section 9.7 : 1.
Section 9.7 : 4.
Section 9.7 : 12.

Week 16 (no homework assigned)
Mon May 2 : Review session with the practice exam and solutions.
Wed May 4 : More review.
Wed May 4 : Additional review session, 6-7 PM, room 165 Everitt Lab.
Fri May 6 : No lecture.