27 April 2014

Matrix Multiplication

When I teach matrix multiplication I find that pupils can get a bit lost in their calculations.  I found a fantastic new method on this blog.

Let's say we have matrix A and matrix B.  We want to calculate AB.  Write down the two matrices side-by-side.  Then move matrix A down. Now write your answer in the space at the bottom right.  I think the next step is self-explanatory from the picture below, but read the original blog post for a full explanation.

I love this method - it's so simple to remember and now almost impossible to get lost when multiplying matrices.

And - on the subject of matrices - this made me chuckle:


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