00:01
This question i'm going to multiply this matrix.
00:03
I have 1, negative 2, negative 1, 2.
00:07
And i'm going to multiply that by 7, 3, 5, and 1.
00:13
First thing i need to do is check the dimensions.
00:16
So it's going to be row by columns.
00:18
So this has 2 rows and 2 columns.
00:21
This also has 2 rows and 2 columns.
00:24
Since the inside numbers match up, i know i can multiply it, and my answer will be a 2 by 2.
00:29
So let's go ahead and multiply this.
00:33
So how you multiply, you're going to do the first row with the first column, and then you'll move to the second row and do the first column again.
00:43
And then once you're done with that, you'll go back up to the first row and do the second column and keep going.
00:49
So let's look.
00:51
1 times 7 is 7, negative 1 times 3 is negative 3...