### Math 221 - Linear Algebra - Reading Assignments December 1999

Be sure to check back, since these may change.

All numbers indicate sections from Linear Algebra and Its Applications by David Lay.

### For December 2

Section 6.3 Orthogonal Projections
• To read : Through Example 3
• Be sure to understand : Figure 2 and the statement of the Best Approximation Theorem

Email Subject Line : Math 221 12/2 Your Name

Let y=(1,2,3) in R3 and let W be the xz-plane.

1. What is the orthogonal projection of y onto W?
2. Is there a point in W that is closer to y than the orthogonal projection you just found? Why or why not?

### For December 7

Section 6.5 Least Squares Problems
• To read : Through Example 3
• Be sure to understand : The definition of a general least squares problem and the statement of Theorem 13

Email Subject Line : Math 221 12/7 Your Name

1. In your own words, what is the point of the section? (Don't just quote the text.)
2. Does every system Ax=b have a least squares solution? If it exists, is it unique? Explain.

### For December 9

Section 6.6 Applications to Linear Models
• To read : Through Example 3
• Be sure to understand : Examples 1, 2, and 3

Email Subject Line : Math 221 12/9 Your Name

1. In your own words, what is the point of the section? (Don't just quote the text.)
2. What is surprising about being able to use linear algebra to solve Example 2?

### For December 14

The REALLY BIG PICTURE. Last day of class. No Reading Assignment.

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