Here is a link to the actual assignment, in case you don't have it handy:

You will need to study Lesson 6 (Determinants and Their Properties), Lesson 7 (Adjoint Matrices), and Lesson 8 (Cramer's Rule) to prepare for assignment 5.

Do note that this means you have never had an assignment that involves the concepts of Lesson 11 (Vector Spaces and Subspaces), Lesson 12 (Linear Independence), and Lesson 13 (Basis and Dimension).  However, your course materials do teach these topics and they may appear on your final exam.  If you look at the sample final exams they provide (and you certainly should, as they are a good indication of what you can expect on your exam), you will see that Lesson 12 is always on the exam.  I think you should also familiarize yourself with Lessons 11 and 13 to be safe, but realize that Lesson 11 is pretty challenging (and, thankfully, is unlikely to be on the exam).

OMIT LESSONS 15 AND 16!
Lesson 15 (Linear Transformations) and Lesson 16 (Eigenvalues and Eigenvectors) is definitely not in the distance course.  Those topics are only taught in the classroom lecture course.

Don't have my book?  You can download a free sample of my book and audio lectures containing Lessons 1, 2 and 9:

Standard determinant problem similar to my Lesson 6, question 1(c).  Check your answer by using a different row or column to expand along.

Similar to my Lesson 6, question 6(b).  Check your answer by using expansion to compute the determinant.

Similar to my Lesson 7, question 1.

Similar to my Lesson 8, question 1(b).

Similar to my Lesson 6, question 2.  Also be sure to look at my Lesson 7, question 3.

Similar to my Lesson 6, question 5.