Week #

Homework problems

Due date

11

Final Exam (Thursday, May 15th, 10:00am) (Solution published).
Quiz 09 (Tuesday, May 6th) (Solution published). Topic: method of integrating factor.
Quiz 10 (Thursday, May 8th) (Solution published). Topic: method of undetermined coefficients.
You'll need to be able to propose the right form for particular solution.
Sample final exam problems:
Sec. 2.1(1.2): 18;
Sec. 2.5(2.4): 12 (find implicit analytical solution using partial fractions);
Sec. 3.3(3.3): 13;
Sec. 3.4(3.4): 6;
Sec. 3.5(3.5): 11;
Sec. 4.3(4.3): 41 (reduction of order, not present in 2nd Ed., see lecture);
Sec. 4.4(4.3): 39(59);
Sec. 4.6(4.5): 5, 7, 28;
Sec. 4.8(4.7): 17, 22;
Sec. 5.6(5.6): 6;
Sec. 7.2(7.2): 7.
There will be 8 problems on the final exam. You can have a page (both sides) of information with you.
You shall get Laplace transforms table. No calculators are allowed!


10

Quiz 07 (Thursday, April 24th) (Solution published). You need to be able to determine type of a critical point of a linear system of ODEs and sketch the phase portrait.
Quiz 08 (Tuesday, April 29th) (Solution published). You need to be able to find critical points of nonlinear system and analyze them.
Sec. 5.7: 1, 2, 5;
Sec. 7.2: 1, 3, 5, 7, 9, 11.
Matlab Problem: Study Example 3 on p.109ff of Polking.
Redo the problem using the initial condition x_1(0)=1, x_2(0)=0.

April 29th, 2014, class time.

10

Second MidTerm Exam (Tuesday, April 15th) (Solution published).
You will have a table of Laplace transforms and also you can have ONE page (one side) of whatever you like.
Sample problems for the exam: BB 4.3, p. 252: 55; BB 4.5, p. 273: 7; BB 4.7, p. 292: 16;
BB 5.4: 8, 11; BB 5.6, p. 357: 3. Also the reduction of order technique is recommended for review.
Quiz 06 (Tuesday, April 8th) (Solution published). You need to be able to use method of variation of parameters for a second order ODE.
BB 5.2: previously you have solved problems for Section 4.5: 14, 16, 18 on p. 272.
For these problems (from BB 4.5) find the Laplace transform (LT) of the solution as directed
on p. 325 for problems 1221.
Then show it is the same as the LT of the solution
determined on p. 273.
BB 5.3: 6, 924;
BB 5.4: 2, 4, 6, 8, 10;
(you will need to use the techniques from BB 5.3 to find
the inverse transform, as e.g. in problems 924 pp. 334335);
BB 5.5: 7, 9;
BB 5.6: 3, 7, 8.

April 15th, 2014, class time.

9

Quiz 05 (Thursday, April 3rd) (Solution published). You need to be able to use method of undetermined coefficients.
BB 4.6: 1, 2, 4, 13, 16, 17, 18;
BB 4.7: 2, 4, 10, 12, 14.
BB 5.1: 4, 16, 20, 24;

April 3rd, 2014, class time.

68

Quiz 04 (Thursday, March 13th) (Solution published). Topic: Homogeneous ODEs of the second order with constant coefficients.
You have to start doing problems before the quiz!
BB 4.1: 15 (give reasons);
BB 4.2: 8, 10, 20, 21, 24;
BB 4.3: 1, 2, 14, 4, 41;
Supplementary material:
In 2 and 14(b), sketch the PPP by hand. You are not asked to use PPlane. In 10b use PPlane.
BB 4.3: 6, 12, 23, 42. Note that 42 is an extension of 12;
Extra problem: Explain why the spirals in the context of Sec. 4.4 are always CW;
BB 4.4: 1,2;
BB 4.5: 2, 9, 10, 13, 14, 15, 16, 18, 27;
BB 1.2: 39.

Tuesday, March 25th, 2014, class time.

5

Canceled! Quiz 04 (Tuesday, February 25th) . Topics: Systems of linear first order ODEs.
Additional reading on complex numbers.
Exam 1 (Solution published)(Example)
(Thursday, February 27th). This homework is a practice. All previous quizzes will be included as well.
(1) BB 3.4: 2, 7. Include a sketch of the phase plane portrait drawn by hand.
(2) BB 3.4: 10. Include the general solution and a sketch of the phase
plane portrait drawn by hand
(3) BB 3.5: 7, 8. Find the general solution and solve the IVP. No plots are required.

February 25th, 2014, class time.

34

Quiz 02 (Thursday, February 6th) (Solution published). Topics: Method of integrating factor.
Quiz 03 (Thursday, February 13th) (Solution published). Topics: Euler method, local and global errors.
BB 3.1: 14, 16, 18, 22, 34, 38.
BB 3.2 and 3.3: 17 p.150 and 9 p.167
(1) BB 3.2: 22
(2) BB 3.2 and 3.3: 17 p.150 and 9 p.167
(3) BB 3.2 and 3.3: 18 p.150 and 11 p.167 and 16 p.167.
In 16 also find an IC such that x(t) > 0 as t > infinity
(4) BB 3.3: 2, 13, 18, 20;
(5) BB 3.4: 3, 8;
In problems (2), (3), (4) and (5) use Polkings PPLANE as discussed in his Chapter 7 (PA)
to draw the direction fields and phase plane portraits.

February 18th, 2014, class time.

12

Quiz 01 (Thursday, January 23rd) (Solution published). Topics: product rule, chain rule, table integrals, integration by parts.
Download any version of dfield you like (dfield8 for example) and any version of pplane (pplane7 for example)
from Polking's web site.
Here is author's original download page for MATLAB scripts.
BB Sec.1.1: 1, 3; use Matlab and dfield8 to plot dfields.
Solve each of the following two initial value problems and plot the solutions for several values of y_0.
Then describe in a few words how the solutions resemble, and differ from, each other:
1a. y'=y+5, y(0)=y_0;
1b. y'=2y+5, y(0)=y_0.
previous two problems do in two ways:(I)find solution and plot it using Matlab's ezplot (see p.9 in PA)
(II) use Polkings dfield to obtain a plot of the dfield with several solutions
BB 1.2: 13, 15, 16.
BB 1.3: 1, 9, 16; use the eul.m script (see the link for scripts above), do 1 step by hand to check code.
BB 1.4: 8, 13, 14;
For Matlab exercises show your matlab work. BE NEAT for full credit;
BB 2.1: 1,9,10,12; use ezplot or fplot for graphs
BB 2.4: 2,4,10,12; In problems 2 and 10 find the solution using the
separable technique and partial fractions and verify your sketch.
BB 2.7 p.109. Use eul.m and rk2.m to check the table on 2.7.1.
rk2.m implements the Improved Euler.
For the following problems from Polking you have to do two parts:
(a) Find teh exact solution (if not mentioned otherwise!);
(b) Use MATLAB to plot on a single figure window the graph of the exact solution(if not said otherwise),
together with the plots of the solutions using each of the three methods (eul.m, rk2.m, and rk4.m)
with the given stepsize h. Use a distinctive marker (type "help plot" for help on available markers)
for each method. Label the graph appropriately and add a legend to the plot.
I. Problem 1 p.72 Polking. You will need to download rk4 from Polking's web site.
x'=x*sin(3t), with x(0)=1, on interval [0,4]; h=0.2.
II. Follow the instructions about MATLAB above (you don't need exact solution!!!) for the IVP
y'=t^2 + y^2, with y(0)=1, on [0,1]; h=.1 and .01. Can you estimate the blow up point?
This problem does not have a solution in terms of elementary functions, it does have a
solution in terms of Bessel functions.
III. Solve the IVPs y'=y^2 and y'=1+y^2 with y(0) =1. Discuss the forward
interval of existence. In this case it corresponds to where the solutions blow up.
Use the direction fields to argue that the solution in II blows up in between the other
two blow up points.

February 4th, 2014, class time.

