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Math 51
Fall 2009
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Weekly Homework Policy

Completing homework assignments is an integral part of this course. Problems are designed to reinforce concepts covered in lecture as well as to encourage students to explore implications of the results discussed in class. Very few students will be able to go through the entire course without struggling on many problems, so do not be discouraged if you do not immediately know how to solve a problem. In confronting difficult questions you should consider how the problem at hand connects to topics, definitions and/or theorems discussed in class.

When you have worked on a problem for a while and remain stuck, you are encouraged to ask for hints from your instructor or TA. Students may also discuss problems with one another, but must write solutions on their own. In particular if you have taken notes while discussing homework problems with friends or instructors, you must put these notes away when writing your solution. Be warned: watching someone else solve a problem will not make homework a good preparation for tests. Don't get caught in the trap of relying on others to get through homework assignments.

Students are expected to take care in writing their assignments. For instance,

  • assignments should be written neatly;
  • assignments should contain clear, complete solutions; and
  • solutions sets which contain multiple pages should be stapled.

Assignments are due to your section leader at 3:30pm on Wednesdays -- no late submissions will be accepted. (This is as much a courtesy to the grader as an incentive to stay current with the course and not fall behind. To accommodate situations such as a serious illness, your lowest homework score will be dropped at the end of the quarter.) Please note that you will not receive credit for work turned in to another section leader. Remember to turn in your homework to the TA of the section you are enrolled in.

Partial progress toward solutions on problems will be awarded partial credit, but simply writing answers down without justification will receive zero credit. Please note that usually only a portion of each week's problems will be scored; the selection of problems chosen to be graded will not be announced in advance.

Assignment Due Exercises Extra Problems (Required)
1 9/29 L1 # 4,5,8
L2 # 1,14,16
L3 # 2,6,7,12
L4 # 2,7,9,14,20
L5 # 5,10,18
Solutions 		Suppose you manage a mutual fund that invests in 1,000 companies. Let S be the vector in R1000 whose ith component is the number of shares of company i that you have today. Let P be the vector in R1000 whose ith component is today's price per share of company i's stock. Express the total value of your holdings in terms of vector operations.
2 10/6 L6 # 4,7,13
L7 # 2,3,5
L8 # 3,9,14,26
L9 # 3,4,13
L10 # 13,16,17,21,22
Solutions (revised 10/9 to fix mistakes)
3 10/14 L11 # 1,13,14
L12 # 6,7,13
L13 # 3,6,8,19,22
L14 # 1,12,14
(As noticed by Max Buranaphong, in Exercise 13.3, the second component of f should be -5x1+2x2, not -5x1+2x1. See the errata page. The question does make sense in its original form as well, though, and if you have already solved the question in that form, you don't need to go back and change your work. In problems 14.12 and 14.14, find the matrix for T.)
Solutions (Answer to 12.13(b) revised 10/15.)
4 10/21 L15 # 1(acdgh), 3, 4
L16 # 2,8,16,19,20,23
Solutions 		Additional problems (required)
5 10/28 L17 # 3,6,11,14,16
L21 # 1,5,8,12,13,14
L23 # 1,7,8,10
There is a mistake in problem 23.10(a). Moreover, problem 23.11 (which is not assigned) is wrong. See the errata page.
Solutions
6 11/4 Levandosky 25: 4
In the following problems find eigenbasis (not necessarily orthonormal): 7, 8, 9, 10, 15, 17.
Licata 2.7: 1, 2, 9, 12, 30, 33.
Licata 7.5: 11, 15, 18, 28, 29(!)
Solutions
7 11/11 Problems (revised 11/5)
Solutions
8 11/18 Problems (revised 11/14)
Solutions
9 Problems (Problem 9 revised 11/20)
This assignment will not be graded. However, similar problems might appear on the final exam.

Fall 2009 -- Department of Mathematics, Stanford University
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