Ok so we’ve cover matrix transpose and multiplication, we’re now going to get into determinants. I’ll spread this into multiple posts as we’ll be eventually dealing with recursive functions. Determinants are a crucial glue in matrix math which allow you to find the inverse, which is akin to the reciprocal.

With the a 2 x 2 matrix, the determinant is single function – once we deal 3 x 3 and greater sized matrices we essentially recursively break them down to 2 x 2 and pass the base function. For a 2 x 2 matrix:

A B

C D

All we need to do is multiply the first element of the first row by the last element of the last row (A*D), and first element of the last row by the last element of the first row (C * B). Then take these away from each other (AD) – (CD) to give us our determinant:

1 2

4 1

(1*1) = 1

(4*2) = 8

(1-8) = -7

= -7

We’ll dig into 3 x 3 matrices next and then onto recursive methods…

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is the (AD) – (CD) meant to be (AD) – (CB)?

thanks!

i love your blog, it’s helped me with so many math assignments. you’re a lifesaver!