00:01
Alright, let's solve the following system.
00:03
With this one, you just have to be careful because it looks like they're two terms for each equation, but they are using different variables.
00:11
Just make sure when you do set up your matrix, you're putting zeros in where they belong.
00:20
So i've got 210 -9 -4, 0 -2 -4 -0 -2 -40, 3 -0 -0 -9 -2 -1 -11.
00:30
So i'm putting it in the form x, y, so we've got some room.
00:41
All right, i am going to, i'm going to use r1 to get rid of r3.
00:52
Okay, we'll do it this way.
00:57
R3 minus r1.
01:03
2 -10 -9 -4, 0 -2 -4 -0 -2 -40.
01:08
3 minus 2 is 1, 0 minus 1 is negative 1, negative 2 minus 0, negative 2 minus 0, negative 11 minus a negative 4 is a negative 7.
01:20
Now we'll turn around and we'll go r1 minus 2 of r3.
01:30
So 2 minus 2 is 0.
01:32
1 minus a negative 2 is positive 3.
01:36
0 minus a negative 4 is a positive 4.
01:40
Negative 4 minus a negative 14 is a positive 10.
01:47
2, 4, 0, 1, negative, 2, negative 2, negative 7.
01:56
All right, we can do the same idea with row 2.
01:59
We're going to use row 2 to work on row 1, so we're going to go row 1 plus row 2...