Math 140: Unit 9

Target Date: Tuesday Dec. 1
Deadline: Friday Dec. 4

Note: The information on this page is for the 8th edition of the textbook.
Click here for the 7th edition information.
Click here for the 6th edition information.

Table of Contents:

Topics
Study Guidelines
Unit Pretest and Exam Description
Checklist

Topics

The material in units 9 and 10 is much different than in most of the other units. In these units, instead of working primarily with functions, you will study systems of equations. We will start with small (2x2) systems of linear equations. These small linear systems are easy to solve via the substitution method. However, that method is very poor for larger systems, so you will then learn how to solve linear systems using the elimination method (the proper name is Gauss-Jordan Elimination). Systems of linear equations arise in many applications in many fields, and also in many areas of mathematics, so solving such systems is an important skill to learn. Therefore, no calculator is allowed for Unit 9.

• Systems of Linear Equations: two equations in two variables (11.1)
  • Solve by substitution
  • Solve by elimination
  • Inconsistent systems
  • Dependent systems
  • Number of solutions
  • Applications
    
    
• Systems of Linear Equations: three equations in three variables (11.1)
  • Solving three equations in three variables
  • Identify inconsistent systems
  • Solving a system of dependent equations
    
    
• Systems of Linear Equations: Matrices (11.2)
  • Matrices
    • Augmented matrix of a system
    • Reduced row echelon form
  • Elimination method using augmented matrices

Study Guidelines for the 8th edition of Sullivan's Precalculus

These reading and problem assignments are designed to help you learn the course material. You should complete all of these problems, check your answers in the back of the textbook, and get help with the problems that you missed. Most of the problems are odd-numbered, so you can check the solutions in the Solutions Manual.

The only way to learn mathematics is to do mathematics, so while these problems will not be collected or graded, you will probably not do well in the course if you do not complete these and check your work as described above. After completing these problems, go on to the Unit Exam Description below and follow directions.

• Section 11.1 : Systems of Linear Equations: Substitution and Elimination
  • Review section 1.3 and appendix A.6 before you begin this section.
  • Reading: section 11.1
    Read and work through examples 1-11 and their matched problems.
  • You should be able to solve systems of two equations in two variables and identify those systems that are inconsistent.
    You should also be able to solve systems of three equations in three variables and identify those systems that are inconsistent.
  • Practice Problems: 11.1 #1, 2, 9, 13, 19, 23, 25, 29, 37, 45, 47, 49, 53, 57, 59, 61, 65
  • Study the applications involving 2x2 systems (for example, problems #55-68 and #71-72). Applications involving 3x3 systems (such as problems #69-70 and #73-81) will be covered in Unit 10.
    
    
• Section 11.2: Systems of Linear Equations: Matrices
  • Reading: section 11.2
    Read and work through examples 1-9 and their matched problems.
  • Learn how to use augmented matrices to solve systems of linear equations.
  • Practice Problems: 11.2 #7, 11, 13, 19, 21, 27, 29, 31, 37, 41, 49, 51, 53, 65
  • Applications involving 3x3 systems (such as problems #73-88) will be covered in Unit 10.
    
    
• Supplementary material (optional):
  • Student Solutions Manual
  • Algebra Review booklet
  • CD lecture series (step-by-step video examples on CD)
  • For tutoring help, visit the Prentice Hall Tutor Center. Tutors can be contacted by phone, fax, or e-mail. To register, you will need the access code that came with your textbook.
  • Graphing Calculator Help

Unit 9 Pretest and Exam Description

After completing the above work, do the following:

1. Read the exam description:
   • No calculator is allowed for Unit 9.
   • This exam has 12 questions, and will count 15 points toward your grade.
   • The exam has a one hour time limit.
   • Remember that applications involving 3x3 systems will be covered in Unit 10.
   • Be sure to look under the entry box for the expected format of the answer.
     • Some problems require you to enter the augmented matrix of a system. There will be a blank for each entry of the matrix, and you can move between blanks using the TAB key or your mouse. However, note that there will be no vertical line between the last two columns in these particular problems.
2. Complete the online Unit 9 Pretest assignment. You may use your book and notes if you wish.
   • Directions: Click on the link above, then choose the Unit 9 Pretest.
   • The pretest must be completed by the deadline date listed at the top of this page.
     However, you may redo the pretest as many times as you like before the due date.
     Your best score counts, and it will be rescaled to 5 points maximum.
3. If you are having trouble with any of the problems listed above or on the pretest, make use of the help resources listed on the Help page.
4. Arrange with your proctor to take the online proctored Unit 9 Exam. Remember to bring identification, and remember that you will not be able to take the unit exam after the deadline date given at the top of this page. You may NOT use your book or notes on this exam.
   • Directions: Click on the link above, then choose Unit 9 Exam.
   • The proctored unit exam must be completed by the deadline date listed at the top of this page, and may be repeated under certain conditions. See the Detailed Schedule page for specific rules.

   Note: Remember that you can always go back and take practice exams on this unit after the deadline has passed. In particular, this will help you prepare for the midterm and final exams.

   • Directions: Click on the link above, then choose Unit 9 Practice Exam. After the deadline has passed, this exam will be available in practice mode.

Unit 9 Checklist

To finish Unit 9, make sure that you have completed the following items:

• Read the material listed in the Study Guidelines.
• Practice the problems listed in the Study Guidelines, and use any of the listed supplementary material to help you understand the concepts.
• Complete the online Unit Pretest (read the exam description first).
• Complete the online proctored Unit Exam.

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