**Linear Algebra**

** (Spring 2021)**

Scroll all the way down for general information about the course. Click here for a PDF file with the course syllabus and policies.

## Week 5 Day 1

In this class session, we will finish talking about Section 2.4: Matrix Inverses and start talking about Section 2.5: Elementary Matrices.

## Week 4 Day 3 (Lab):

Here's a copy of the worksheet we will use in lab:

https://www.dropbox.com/s/jqqg4xz0xocr1ru/M221-Sp21-Lab4-2.4%2C2.5.pdf?dl=0

## Week 4 Day 2 (Rest Day!)

Wednesday, February 17th, is a university-wide rest day! Please take some rest!

## Week 4 Day 1:

In this class session, we will go over Section 2.4: Matrix Inverses.

## Week 3 Day 3 (Lab):

Here's a copy of the worksheet we will use in lab:

https://www.dropbox.com/s/rfpi2xa4jfezouc/M221-Sp21-Lab2-2.2%2C2..pdf?dl=0

## Week 3 Day 2:

In this class session, we will work on Section 2.3: Matrix Multiplication.

Before you come to class, you can think about the following problem:

*Suppose that A and B are two m x n matrices such that A***x***=B***x ***for EVERY n-vector ***x***. What can you conclude about A and B?*

## Week 3 Day 1

In this class session, we will begin Section 2.2: Matrix-Vector Multiplication.

**Before you come to class**, you can attempt to solve the following problem:

*Write the general solution to the following system in parametric form*

x − y − z + 3 w = 2

2 x − y − 3 z + 4 w = 6

x − 2 z + w = 4

## Week 2 Day 3 (Lab):

We worked on the following worksheet in class together: https://www.dropbox.com/s/w7hqmvl3gc8o3ia/M221-Sp21-Lab2-2.1.pdf?dl=0

## Week 2 Day 2

In this class session, we will finish our discussion on **Section 1.3, Homogenous Equations**, and begin **Chapter 2: Matrix Algebra.**

### Before you come to class:

Consider the following problem: *Let A be an n x m matrix of rank r and consider the homogeneous system whose coefficient matrix is A. How many solutions does this system have? How many parameters are in the general solution?*

Homework 1 is due on Friday, Feb 5th, on Gradescope at 1 PM.

## Week 2 Day 1

In this class session, we will finish talking about the *rank of a matrix, *from **Section 1.2.**** **We will start **Section 1.3: Homogenous Equations.**

### Recommended problems from Week 1:

If you'd like more practice from the contents of last week, you can look at the following problems from your book:

1.1.14-1.1.15, 1.1.18-1.1.20, 1.2.12, 1.2.16-1.2.22.

## Week 1 Day 3: Lab

In this class session, we will go over the following worksheet together. If you'd like to print out a copy and bring it with you, you are welcome to download it here: https://www.dropbox.com/s/vtd6davzh641ita/M221-Sp21-Lab1-1.1%2C1.2.pdf?dl=0

## Week 1 Day 2:

In this class session, we will cover the rest of Section 1.1, and start 1.2.

### Before you come to class:

- Please consider the problem: *Describe all solutions to 3x-y+2z=6 in parametric form in two different ways. *

*- *Please fill out the Introductions! survey if you haven't already.

- Please confirm that you can access both Gradescope and Zoom chat! I will ask you to solve a problem in class and send it to me over Zoom chat in real-time.

Please submit by Friday, February 5th at 1 PM EST, over on Gradescope.

## Week 1 Day 1:

In this class session, we will go over the syllabus, expectations for attending an in-person class during a pandemic, and **Section 1.1** of our textbook.

### Before you come to class:

Please carefully read over the syllabus file, make note of any questions you have, and come prepared to ask those questions in class.

At some point during Week 1, please complete the survey titled: Introductions! During class, I will ask you to tell us about yourself in a few sentences. Filling out the survey might help with coming up with an introduction beforehand :)

Here is a famous problem that uses linear algebra for you to think about if you are interested:

(The Hundred Fowls Problem.) One hen is worth 5 qian, one rooster 3 qian, and 3 chicks are worth 1 qian. If we bought 100 fowls with 100 qian, how many hens, roosters, and chicks did we buy?

Important note: Please don't feel discouraged if you cannot immediately solve the above problem. I haven't taught you anything yet! This is meant to give you a flavor of the kinds of things we will be talking about on Day 1.

## Why linear algebra?

## Syllabus.

Click here for a PDF file with the course syllabus and policies.

## Course Websites.

All of the information presented here (and more) is also available on the Canvas site for this course.)

Other than Canvas, we will use Zoom and Gradescope in this class.

## Textbook.

We will use the following textbook which is free to download:

**"Linear Algebra with Applications"**, by*W. Keith Nicholson*, Version 2019 - Revision A.Official website: https://lyryx.com/linear-algebra-applications/. Click here to download a pdf file.

The book consists of eleven chapters, we will cover most parts of the first * eight* chapters.