00:01
First getting this into an augmented matrix, 1, 3, negative 1, negative 7, negative 2, 421, negative 3, negative 7, 11, 59.
00:17
Let's get a 0 in row 2 by adding row 1 and row 2 together.
00:24
That'd be negative 1, 1 plus negative 1, 3 plus negative 2.
00:32
We have 3 and 14.
00:34
Then we can get a zero in row three by taking row three and adding three times row one to it.
00:50
That'll be negative three plus three, negative seven plus nine, eleven plus negative three, and 59 plus negative 21.
01:07
And that's 38.
01:26
Then we can get a 0 in row 3 if we take row 3 and subtract 2 times row 2.
01:36
It'll be 0 minus 0, 2 minus 2, 8 minus 6, 38 minus 28...