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Homework | Exam Info and Seating | Practice Exam, Midterm 1 | Practice Exam, Midterm 2 | Final Exam Info |

The best way to keep up-to-date about the course is via this course's Piazza page. Sign up for this class on Piazza here. (Or look for an activation email from Piazza: data from TED was transferred over and you have been sent an invitation; check your official UCSD email address.)

There is also TED for this course, though it will mostly be a place to check your grades. Piazza will still be the main place for discussion.

The course syllabus, containing most of this information, more official policies, and an approximate lecture schedule, is available in PDF form here.

MATLAB assignments are a required part of this course; it is somewhat independently administered; the schedule and assigments are up on the MATLAB for Math 20D page. Separate written homework will be assigned, but none yet, until I get it all straightened out with TED.

**Office hours:**

Thursdays 4p-6p

Fridays 11:30a-1:30p

Section | Time | TA |

D01 | Tu 4:00p-4:50p | Ashley Chen |

D02 | Tu 5:00p-5:50p | Ashley Chen |

D03 | Tu 6:00p-6:50p | Kuangyi Yang |

D04 | Tu 7:00p-7:50p | Kuangyi Yang |

D05 | Tu 8:00p-8:50p | Kuangyi Yang |

D06 | Tu 9:00p-9:50p | Kuangyi Yang |

Section 1.1: 15-20, 22

Section 1.2: 1(a), 7, 12, 15

Section 1.3: 7, 12, 18, 20

Section 2.1: 1, 14, 15, 16, 19

**Homework 2:** due Wed, Oct 14 at the end of class

Section 2.1: 21,31

Section 2.2: 1, 2, 9, 15, 23, 30(a-e)

Section 2.3: 2, 10, 16

Section 2.5: 3, 6, 7

**Homework 3:** due **Friday**, Oct 23 at the end of class (note the change from Wednesday!)

Section 2.6: 1, 8, 10, 13, 15

Interesting OPTIONAL problem that relates integrating factors to Sec 2.1: 23

Section 3.1: 1, 5, 10, 18

Section 3.2: 3, 5, 7, 9

Section 3.3: 1, 3, 9, 11, 18, 20

**Section 3.4**: 1, 2, 6, 12

**Homework 4:** due Fri, Oct 30 at the end of class

Section 3.4: 23, 25, 28, 31

Section 3.6: 1, 2, 3 (ignore the instruction "check your answer using undetermined coefficients"), 5 (use integral sec(t) dt = ln|sec t+ tan t|), 7, 12 (leave it in integral form), 13 (remember to divide through to get y" by itself).

(hopefully, you'll find this shorter)

**Homework 5:** due Fri, Nov 6 at the end of class

Section 3.7: 26(a) (use general solution with sin and cos as in Section 3.4; and solve for c1 and c2 using the initial conditions, and abbreviate the imaginary part as mu). OPTIONAL, but good practice because I think it'll help develop your feel of DiffEq: 26 (b) and (c) also.

Section 7.1: 5, 6

Section 7.2: 1, 2, 11, 21, 22, 23

Section 7.3: 14

**Note:** Problem 15 (in an earlier edition of this assignment) has been removed. I thought it was a straightforward Wronskian question, but it is definitely a linear algebra subtlety which is beyond the scope of this class.

**Homework 6:** due Fri, Nov 13 at the end of class

Section 7.4: 4. OPTIONAL, for a more solid theoretical understanding of the Wronskian: 2, 3.

Section 7.5: 2, 3, 8, 15 [You can use Matlab Project 4 to help you graph these.]

Section 7.6: 2, 3 [You can use Matlab Project 4 to help you graph these.]

**Homework 7:** Due Fri, Nov 20, at the end of class (we have a midterm that day. I'll put a reminder on the board then). Note also that we're skipping Section 7.7.

Section 7.3: 16, 17, 18, 21 (there's a i sqrt(11) ... do not be alarmed).

Section 7.6: (Some of these were also on the last homework; this time, express the general real solution, i.e. including sines and cosines): 2, 3, 6, 9

Section 7.8: 1, 3, 4, 7

Note that MATLAB Project 4 has been postponed to be due on Monday. You can either use MATLAB project 4 to help you out with the graphing, *or* simply write in a verbal description of what kind of graph it will be, with certain key terms such as *source*, *sink*, *node*, *saddle*, and *spiral*.

**Homework 8:** Due **Wednesday, December 2:**

Section 5.1: 3, 5, 7, 9, 13, 17

Section 5.2: 1, 3, 5, 9, 11

**Last Homework** (no due date: you do NOT have to turn in):

Section 6.1: 1, 7, 9, 11, 15 (this topic may be on the final, so practice!)

The rest of this will **not** be on final but is sort of the logical conclusion and the rhyme and reason for the method of Laplace transforms, for your reference and future classes):

Section 6.2: 1, 3, 5, 11, 13, 39 (use the method of 39 without proof to do partial fractions)

Section 6.4: 1, 3, 5

**Assigned Seating for Exams**

Seats will be assigned for the exams. Each chair in the lecture hall has a small metal label on the part where you rest your back on:

If you prefer a left-handed seat, please contact me about it as soon as possible, and we will change your assignment. To look up your seat assignment, check your grades on TED. There will be an "assignment" labeled "MT1 Seat", and your "grade" is your seat number (see screenshot; it's been underlined):

20D Midterm 1, Fall 2006. This test includes some reference information with the various types of differential equations. This would be a good idea to include on your note sheet. *hint hint*

20D Midterm 1, Winter 2013. (You will only be expected to know the difference between stable and unstable equilibrium solutions, though semistable was covered in a homework problem).

20D Midterm 2, Fall 06 (here are solutions for it). Some comments: Problem 1 actually was mostly covered on the first midterm; the real new material is the Variation of Parameters. Like that professor, I will tell you the necessary integrals if they involve anything like trig sub or (God forbid) partial fractions. Skip 4c; we did not do that in class.

20D Midterm 2, Spring 15 (I'll post solutions soon). For problem 3, instead of using undetermined coefficients, use variation of parameters. This is a considerably easier exam than the previous practice, and ours will be closer to this one (but there will likely be a separate "reduction of order" problem).

Our Midterm 2 will be 4 questions long (instead of the 5 of the last midterm).