# Math 2325 Intro to Higher Math -- Assignments

## Dr. Duval

### Chapter 1, Linear Iteration

Report due Monday, February 19.
Revised report due Wednesday, March 7.

Your main goal is to determine when the sequence converges (that is, for which values of a, b, and x_0 does it converge), and, when it does converge, to which limit? These questions are closely related, and working on either one will help you with the other.

The first part of this goal (when does it converge?) involves addressing Question 5 (you may want to, but do not have to, organize your answer along the lines suggested by Question 6). The second part of this goal (about finding the limit) involves addressing Questions 7 and 8.

### Chapter 9, Parametric Curve Representation

Report due Wednesday, February 28.
Revised report due Wednesday, March 21.

Your main goal is to answer the question "Which properties of the parametersp, q, r, s determine the symmetry of the parametric curves

x(t) = sin(pt) + cos(qt)
y(t) = sin(rt) + cos(st)?".
This is, essentially, the last part of Question 2. Question 1 and the first part of Question 2 are good warmups, so do those first; they can also be your first data points. It is also helpful to do Exercises 1-3, some pieces of which can also be data points.

### Chapter 3, Euclidean Algorithm

Report due Monday, March 26.
Revised report due Wednesday, April 11.

Your main goal is to investigate the following:

• The number of steps the Euclidean algorithm takes to compute the GCD of two Fibonacci numbers; and
• the GCD itself of two Fibonacci numbers.
In each case, your answer should depend on the position in the Fibonacci sequence of the original two numbers.

This is largely a restatement of Question 6, which provides a good way of attacking the problem: sorting the Fibonacci numbers by how far apart they are in the Fibonacci sequence, starting with those that are close to each other in the sequence. In particular, it would be more valuable to prove some of the results you get by answering Question 6 than to completely answer without proof the main goal listed above.

Also compare the answers you get to the corresponding answers for non-Fibonacci numbers in Questions 2 and 3.

Final note: Some of your answers could depend on how you index the Fibonacci sequence. The standard numbering is that F_1=1, F_2=1, but the notebook we are using defines F_1=1, F_2=2. You may use either one, but some things may be easier to state and/or prove using one indexing or the other.

### Chapter 14, Iteration of Quadratic Functions

Report due Wednesday, April 4.
Revised report due Wednesday, April 18.

Your main goal is to determine when the sequence has:

• attracting fixed points;
• repelling fixed points; and
• 2-cycles.
You should also identify these fixed points and 2-cycles. You do not have to identify if the 2-cycles are attracting or repelling.

In other words, for which values of a do you get attracting fixed points, repelling fixed points, and 2-cycles, and what are the values of these fixed points and 2-cycles?

This goal can be approached by answering Questions 1, 2, 3, and 7. Question 4 may also be helpful in finding values of a to exclude.

Question 6 is also very interesting, but is more of a lead-in to the rest of the lab, which you might consider doing for your optional 7th lab, if you like the idea of chaos, or want to learn more about it.

### Chapter 7, Polyhedra

Report due Monday, April 23.
Revised report due Friday, May 11.

There are three main goals of this lab:

1. Consider the well-known Euler relation on vertices, edges, and faces of "most" polyhedra: E = V + F - 2. Show how constructions, such as stellation, affect this formula. In other words, show the inductive step of an inductive proof of Euler's formula. In other words, show that if you start with a polyhedron that satisfies Euler's relation, then stellate it (or do other similar operations), the resulting new polyhedron will still satisfy Euler's relation.

[Caveats: Euler's formula is only true for polyhedra that are "spherical", that is, those that can be thought of as a sphere with all the roundness smoothed out into flat spots corresponding to the faces of the polyhedron. For instance, it is not true if you make a polyhedron that resembles a donut! So, you cannot expect a "proof" to show it is always true. But your inductive step can still work, because you can't make a donut-polyhedron out of a sphere-polyhedron by stellating!]

2. Find all regular polyhedra. Prove your list is complete.
3. Find formulas (beyond Euler) for polyhedra with just triangles and squares. In other words, find relations among the numbers of vertices, edges, triangles, and squares.

To attack this problem, it is a good idea to first consider polyhedra with just triangles. Then try polyhedra with just squares. Then, finally, try mixtures of triangles and squares.

There are not so many formal questions in the text this time that are as directly related to the main goals. But the general discussion of polyhedra may be helpful to you.

### Chapter 6, Randomized Response Surveys

Report due Wednesday, May 2.
Revised report Friday, May 11.

Your main goal is to answer the question: "What should the survey-taker do with the results?" In other words, what is your estimate of the proportion of True Yesses as a function of the proportion of reported yesses? Answer this in the most general setting, where the probabilities of answering the real question (dime lands heads) and the answer to the decoy question being yes (penny lands heads) are variables.

This is some mixture of Questions 1-3, 8, and 11.

### Optional 7th Lab

Report due Friday, May 11.
No official revisions, but I encourage you to consult with me as you write your report.

Talk to me in advance so that we can set up a reasonable main goal for you to pursue.

Also note that, instead of an optional 7th lab, you may turn in a re-revision of any of the first six reports, or you may turn in nothing at all. (See syllabus for how all this affects your grades.)