Math 217 Fall 2015

Lectures: MWF 10:10am-11:00am and 11:10am-12:00noon Wilson 214

Instructor: Songhao Li **Office:** 207A Cupples I

**Phone:** (314)935-4208** email****:** sli (at) math (dot) wustl (dot) edu

**Office Hours: **Monday 1pm-2pm, Tuesday 1pm-2pm and Wednesday 2pm-3pm or by appointment

**Office Hours for the Final Exam: **Tuesday Dec 8 1:30pm-5pm, Wednesday Dec 9 2:30pm-5:00pm

**Note: **TA office hours are as usual on Monday Dec 7 and on Thursday Dec 10

**TA:** Gong Cheng

**TA Office Hours:** Monday 3pm-5pm Thursday 3:30pm-4:30pm Lopata 323

**Calculus help room:** http://www.math.wustl.edu/~blake/calculus/

**Grader:** Fan Zhang, Taylor Lau, Augus Gu, Amritha Gourisankar

**Course Webpage:** http://www.math.wustl.edu/~sli/math217_fall2015/course.html

**Textbook:** *Elementary Differential Equations 10ed by* Boyce and DiPrima

**Suggested:** *Elementary Differential Equations with Boundary Value Problems by* Edwards and Penney

Note:
Boyce and DiPrima has a different version *Elementary Differential Equations and Boundary Value Problems 10ed*.

As far as I checked, the first nine chapters are just the reproduction of our textbook.

Edwards and Penney is optional. I listed it here because it has been used for this course at this university in the past.

It is preferrable if you can get the 10th edition of Boyce and DiPrima.

If
you elect to use an earlier edition, it is your responsibility to check
the possible different numbering in homework assignments.

Syllabus:

If time permits, we will cover up to Chapter 7 of Boyce and DiPrima, possibly skipping some sections.

More details to follow...

COURSE GRADE:

There will be four exams, three of which will be written on weekday evenings during the semester, plus the final exam.

The final exam is accumulative.

There will be weekly homeworks, except on the weeks preceeding the exams.

Instead, there will be a webwork during the week before each exam.

Each of the homework assignments and the webworks will be counted equally.

Update: The point grade for the course will be the greater of the following two options:

1. 20% homework/webwork + 20% E1 + 20% E2 + 20% E3 + 20% F

2. 100% F

Your point grade is then translated into the letter grade, with the class average being at least B.

Midterm point grade is calculated as follows:

0.2 x E1 + 0.2 x E2 + 0.05 x A1 + 0.05 x A2 + 0.05 x A3 + 0.05 x A4 + 0.05 x A5

The maximum point grade is 50.

Ave: 36.989, Median: 37.65

Range: A: 40-50, B: 34-39.99, C: 28-33.99, D: 22-27.99, F: 0-21.99

Distribution: A: 61, B: 60, C: 34, D: 17, F: 3

Note that for convenience, I did not add + or - to the letter grades, and I did not include the one and only webwork in the calculation.

I will add +/- and include the webwork for the end-of-course grades.

The exam dates:

Exam 1: Sept 17, Thursday 7pm-9pm

Exam 2: Oct 20, Tuesday 7pm-9pm

Exam 3: Nov 17, Tuesday 7pm-9pm

Final Exam: Dec 11, Friday 10:30am-12:30pm

You can look up your seating here.

http://www.math.wustl.edu/seatlookup/

The following exam sessions are lead by our TA Gong Cheng

Exam 1 review session: Sept 14, Monday 6pm-8pm Wilson 214

Exam 2 review session: Oct 15, Thursday 6pm-8pm Wilson 214

Exam 3 review session: Nov 13, Friday 6pm-8pm Wilson 214

Final exam review session: Dec 9, Wednesday 6pm-8pm Wilson 214

Exam 1 Exam 1 Solution Histogram Ave: 69.986, Median: 72

Exam 2 Exam 2 Solution Histogram Ave: 71.069, Median: 72

Exam 3 Exam 3 Solution Histogram Ave: 60.305, Median: 59

Final Final Solution Ave: 55.825, Std Dev: 15.047

Note: The answer for #2 is B, not A as indicated on the grading site. The discrepency will be resolved later.

Also no matter what you choose for #8, you will get the credit.

IMPORTANT INSTRUCTIONS:

Print the homework sheet and use it as the cover sheet.

Write your student number and your name clearly on the cover sheet.

Please use letter sized papers only, and remember to staple your homework.

Anyone who fail to do this will be subjected to a 10% penalty.

Note:
For the direction fields and the graphs of solutions, you may use the
printouts from a software or a website, or you may simply hand draw them.

In either case, do not spend too much time on the pictures.

The pictures are supposed to help building intuition.

They are not meant to waste your valuable time.

Webwork 1 is posted, due Sept 18, 2015

Note: To limit the workload, I have not assigned too many problems in Assignment 8.

Try practising with similar problems in the textbook and in past exams to prepare for Exam 3.

Aug 28: Classification of differential equations

Sept 4: 1st order separable ODE's

Sept 11: Uniqueness and existence of solutions as in Sec 2.4

Sept 18: Characteristic equation: b^2-4ac > 0

Sept 25: Characteristic equation: b^2-4ac < 0

Oct 2: Methods of undetermined coefficients