00:01
So the first thing i'd like to do is create a matrix.
00:03
So the top row is going to be 2, 4, negative 3, negative 18.
00:14
Then i'm going to have 3 -1, negative 1, and negative 5.
00:25
Then 1, negative 2, 4, and lastly, 14.
00:35
So the first thing i'm going to do is i'm going to do a little bit of just reordering here.
00:40
I'm actually going to move this bottom row up to the top.
00:43
Because now my first step is done.
00:47
My upper left corner is a 1.
00:51
So now i'm going to use that row to help me with the other two.
00:56
So let's just, let's keep the middle row the same.
01:01
We'll just have slipped 1 and 1 and 3.
01:03
So if i multiply the top row times a negative 3 and add it to my middle row, i'm going to have 0, positive 6, and a 1.
01:12
So 7.
01:15
Negative 3 times 4 is negative 12, minus 1.
01:17
Is negative 13.
01:25
So 14, i'll do that over here, so you can see what i'm talking about 14 times and negative 3, it's going to get me negative 42, minus 5, it's going to get me negative 47.
01:45
Then, last but not least, let's work on the bottom row.
01:50
So i'm going to take the top row here and the top row on both equations.
01:56
But on this.
01:57
One here i'm going to multiply it times a negative 2.
02:00
So that means 0, 8 and 4 is 12, negative 8.
02:10
Oops, actually, let's back up here.
02:14
So i'm multiplying this by it.
02:15
So i'd have negative 2 and negative 2 would be positive 4, and 4 and 4 would be 8.
02:21
Negative 2 and 4 is negative 8, plus 3 is negative 11.
02:27
And 14, doubled is 28, but it's going to be negative 28.
02:31
And a negative 18.
02:34
Write that over here, so you can see what i'm talking about.
02:35
Negative 18, negative 28, is negative 46...