00:01
We are asked whether we think the commutative property holds true for matrices.
00:06
In this case, meaning a times b would be equal to b times a.
00:11
Well, a quick way to try and prove that would be to go ahead and start doing that multiplication.
00:17
We don't have to do the entire thing, but we can do parts of it at least.
00:21
So we'll set up matrix a, a11, a12, a21, a22, and we'll set up matrix a, a21, a22, and we'll set up matrix a, and we'll set up matrix b, b11, b12, b21, b22.
00:41
We know when we multiply matrices, we're supposed to take rows times columns.
00:46
So we would take this top row times this left column to begin with.
00:52
So if we did that, we'd be taking a11 times b11.
00:59
Then we'd be adding that to a12 times b21.
01:06
Right? that would be the top left of our answer matrix.
01:10
All right.
01:11
So now let's take b times a.
01:14
Let's set that up.
01:16
So b matrix comes first.
01:18
B11, b12, b21, b22...