00:01
So here we're given the system x.
00:05
The first thing we're going to do is find the augmented matrix.
00:10
So 1, minus 2, 1, 4, 2, 2, minus 2, minus 1, 1, 1, 4, 1, 7.
00:23
Now what i want to do is cancel out everything under my first pivot position 1.
00:29
So i'm going to multiply row 1 by minus 2, and add it to row 2.
00:37
From here on i'm going to stop reading the steps up.
00:50
Here we get 0, and then minus 2 times minus 2 is 4, 4 plus 2 is 6, minus 2 times 1 is minus 2, plus minus 2 is minus 4.
01:07
Minus 2 times 4 is minus 8, plus minus 1 is minus 9.
01:13
And then what i can also do is negate row 1 and add it to row 3.
01:18
So i get 0, 2 plus 4 is 6, minus 1 plus 1 is 0.
01:43
Let's see.
01:45
So we have 1, 4, 17.
01:52
Okay, so yes, we can negate the first row and added to the last row.
01:56
So there's 0, 2, plus 4, 6, minus 1, plus 1 is 0, and 4, and minus 4 plus 7 is 3.
02:16
Well then now i can negate the second row and add it to the third row.
02:24
So this becomes negative, if you can negate negative 4, you add it to the third very good 4.
02:31
And then 9 plus 3 gives us 12...