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## Homework Statement

Hi all. I am doing this work and cant seem to find any information on this in any of my notes or text books. The question is, "Evaluate (if possible) AB, BA, CD and DC", this is what i need some help with.

I also have further on the question, "Evaluate | u |, | v |, u . v and u * v", but this one i can do already so i dont need help with this one.

I know that a single matrix can't be evaluated exactly and since i cant find anything on evaluating either a single matrix or multiple matrices, i assume at the moment that, it is not possible to evaluate these from the first question either?

The relevant equations are below:

[tex]

A = \left(\begin{array}{c} 21 \ 60 & 2 \ 7 \end{array}\right)

[/tex]

[tex]

B = \left(\begin{array}{c} 4 \ -5 & 3 \ -2 \end{array}\right)

[/tex]

[tex]

C = \left(\begin{array}{c} 15 \ 3 \ 7 & 5 \ 12 \ 4 \end{array}\right)

[/tex]

[tex]

D = \left(\begin{array}{c} 3 \ 5 \ 15 & 1 \ -1 \ 7 & -5 \ 1 \ 8 \end{array}\right)

[/tex]

Any help/ information would be greatly appreciated. Thanks

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