Review exercise 1.1. (a) Show the 3 by 3 matrices and for which and .

(b) Find the products , , and of the above matrices.

Answer: (a) We have

and

(b) We have

(As a point of interest, note that and . This follows from equation 1M(i) in section 1.6: .)

NOTE: This continues a series of posts containing worked out exercises from the (out of print) book Linear Algebra and Its Applications, Third Edition by Gilbert Strang.

If you find these posts useful I encourage you to also check out the more current Linear Algebra and Its Applications, Fourth Edition, Dr Strang’s introductory textbook Introduction to Linear Algebra, Fourth Edition and the accompanying free online course, and Dr Strang’s other books.

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I’m glad you like the site and find it useful. (If you have a blog please feel free to link to the site.) Good luck studying linear algebra!