Feedback: Test #2
MA2321, Fall '03, T. Olson

General Info. (applies to all tests)

Each time you get a test back, you should go through it thoroughly (preferably with one or two other students). Make sure you understand what each problem was asking and how to answer each problem correctly, completely, and clearly. If you cannot figure something out, check your notes or textbook. If you're still not sure, go through the test with me or a coach from the Math. Learning Center.

• Marks:
  ``$\surd$'' $\Longrightarrow$ Correct
  ``X'' $\Longrightarrow$ Wrong
  
  ``O.K.'' $\Longrightarrow$ ``Okay, BUT ...'' (I probably gave you full credit, but something is wrong: perhaps your answer was based on an incorrect previous answer or you missed the point of the question or I couldn't tell how you arrived at your answer)
  
  ``+2'' $\Longrightarrow$ partial credit (in a circle)
  

• Numbers/score:
  • At the bottom outer corner of each page is the total number of points you earned on that page.
  • On the top of your first page is your total for the test. Check that your individual page totals add to this number.

Test #2 Comments
You could earn a maximum of 5 points on each question (or part).

Comments on particular questions:

1.

Some of you forgot how to do matrix multiplication!

2.

Even if you can't solve the equations correctly, you should at least write down what equations you need to solve.

3.

You only need to know the eigenvalues of A to answer the second part of this question.

4.

The inverse of P is NOT the transpose of P in this case, even if you try to normalize the eigenvectors.

True/False:

I gave some of you credit on these even without a decent example. Don't count on such generosity in the future.

20.

You could do this one with your calculator, but that's NOT the EASIEST way.

21.

I was looking to see if you knew that the original vector minus the projection was orthogonal to W. BUT I MESSED UP AND SWITCHED THE VECTORS ... if any of you had tried to check your answer, you would have been very confused. But only ONE of you actually did.