00:01
So in this problem, we're given a set of equations minus x1 plus x2 equals.
00:11
I don't even write that very good.
00:13
Let's rewrite that.
00:14
X2 equals 4.
00:17
And minus 2 x1 plus x2 equals 0.
00:24
And we're asked to write a system of equations as a matrix equation.
00:29
A, x equals b.
00:33
And so, to do that, to write a, x equals b, well, the matrix a will be the coefficients from over here.
00:50
So that'll be the matrix minus 1, 1, minus 2, 1.
00:55
Write the coefficients off of all those.
00:57
The x will be our variables.
01:04
And then the b will be everything on the right hand side, written as a matrix there.
01:14
Then it says, use gaussian jordan elimination on the augmented matrix, a -colon b, to solve for the matrix x.
01:26
So what does that mean? that means that we do minus 1 -14, minus 2 -1 -0.
01:36
I'll draw a line here to show that's my augmented matrix.
01:40
And to use gaussian -jordan elimination, then we're going to get this into row -reduced echelon form.
01:54
Gaussian, oh, it's not gaussian, sorry.
01:57
Gouse jordan elimination.
02:08
We use our row operations.
02:11
And so let's do row 1 times minus 2, added to row 2.
02:22
So when we do that, row one stays the same.
02:28
So minus 2 times minus 1, that's a positive 2.
02:31
Added to 2, that's 0.
02:32
That's what we're trying to do.
02:34
1 times minus 2 is minus 2.
02:36
Added to 1 is minus 1.
02:40
And 4 times minus 2 is minus 8 added to 0...