00:01
When you're multiplying matrices, you definitely need to make sure that a couple things line up.
00:05
When we do it, we need to make sure that our number of columns in the first one match up with the number of rows in the second one.
00:14
So there are two columns in the first one and two rows in the second one.
00:18
So since they match up, we know that we're able to do the multiplication process.
00:23
So we're going to start by multiplying the first row from b by the first column of c.
00:30
And the way that we do that, i'm just going to make this nice and big here, we'll do negative 3 times 5, which is negative 15.
00:38
And we're going to add on to it 9 times negative 2, which is negative 18.
00:42
And that's our first element.
00:44
Then we kind of go across.
00:45
So negative 3 times 6 is negative 18, and then 9 times 4 is 36.
00:51
We have plus 36 here.
00:53
And then one more time.
00:54
So negative 3 times negative 8 is 24, and then 9 times 6 is 54.
00:58
And that would be our very first row now.
01:01
Now we're going to move down to the next row and then over to the next column and repeat that process.
01:09
So we'll start off by, i take that back.
01:15
We're just going to go down to the next column or down to the next row and we restart again with the first column.
01:21
So we're here now.
01:23
So four times five is 20 and then 11 times negative 2 is negative 22.
01:29
So we'll do plus negative 22 here.
01:30
And 4 times 6 is 24 and 11 times 4 is 44.
01:36
And then 4 times negative 8 is negative 32 and 11 times 6 is 66.
01:41
We have plus 66 for our next one.
01:43
And then finally for our last one, repeat it, we're going to be down now at this row...
