Differential Equations

Math 23 Spring 2019

Homework

Homework reinforces concepts and skills while challenging students to extend what they have learned to other types of problems. Because it is important for students to have this experience, instructors will not solve assigned homework problems during office hours before the due date. We will of course answer questions you may have in approaching problems that give you difficulty. It is therefore essential to begin homework sets early so that you may get help if difficulties do arise. This is especially true for problems that involve programming.

Homework grading policy: Because the goal of homework is to have students work through problems, homework grading is based on both effort and correctness based on the following 10 point scale: 85% or higher = 10; 81-85% = 9; 71-80% = 8; 61-70% = 7; 50-60% = 6; "reasonable effort" = 5; "little or no effort" = 0. Your lowest homework score will be dropped.

Written homework should be turned in to the homework boxes outside of Kemeny 108 by 3 PM each Wednesday. (unless otherwise stated).

No late homework will be accepted.

Please follow the homework submission guidelines.

Cooperation on homework is permitted (and encouraged), but you must write the solution up on your own. Please acknowledge any cooperative work at the end of each assignment.

Assignment Due Date Problems
HW 1 Friday, April 5 (3 PM) §1.1: #7, 9, 12, 22, 24
§1.2: #5, 12 (Hint: do (b) first), 13
§1.3: #8, 14
§2.1: #15, 17, 30, 33
§2.2: #8, 18, 25
§2.4: #11, 14, 22, 25, 28, 33
Also please submit your FERPA waiver.
HW 2 Wednesday, April 10 §2.3: #2, 4, 8 (Hint: Solve 8 (c) numerically.), 15
§2.5: #4, 12, 15
§2.6: #2, 14, 16, 24, 27
Use exercise 24 in 2.6 to solve the equation $$(3y^2 + 4xy) + (4xy + 3x^2) \frac{dy}{dx} = 0.$$
HW 3 Friday, April 19 §3.1: # 11, 22, 23, 27
§3.2: # 10, 19, 22, 27, 34
§3.3: # 5, 11, 20, 26, 35
§3.4: # 6, 13, 28
HW 4 Thursday, April 25 §3.5: # 9, 14, 18, 29
§3.6: # 11, 15
§7.1: # 7 (only (a),(b)), 15
§7.3: # 11, 25
§7.4: # 2 (only (a), (b), (c)), 5, 6 (only (a), (b))
HW 5 Thursday, May 2 §7.5: # 8, 18, 25, 29
§7.6: # 10, 11, 28
§7.8: # 10, 15, 18 (only (a), (b), (c), (d))
HW 6 Friday, May 10 §9.1: # 18, 20, 21
§9.2: # 15
§7.9: # 2, 3 , 4, 11, 14 (only verify the general sol. of the corresponding homogenenous part)
HW 7 Thursday, May 16 §9.2: # 4, 8 (only (a), (b), (c)), 23
§9.3: # 4, 9, 20, 27
§9.4: # 3, 8
§9.5: # 4, 12

Plotting slope fields and trajectories
Direction field plotter
HW 8 Thursday, May 23 §6.1 # 2, 14, 24
§6.2 # 16, 26, 29, 32
§6.3 # 18, 20, 25 §6.4 # 8, 17
§6.5 # 8, 14, 18
§6.6 # 1, 2, 16, 21