00:01
Okay, let's solve this problem.
00:02
So the first thing you do is you turn it into a matrix, and then you use the role operation to solve it.
00:12
So first we turn it into a matrix.
00:15
1 -1 -9 -1 -3, negative 2, and 1.
00:23
1 -3 -negative 2.
00:27
Okay.
00:30
And here are 6, negative 5, 14.
00:43
Okay, so the next step we do is we label this is row 1, this is row 2, and this is row 3, okay? so the next step we do is to use the role operations to cancel some entries, okay? so the first step we do is we use the row 3 minus row 1, okay? and then we set this new value to row 3.
01:20
So we have 1.
01:37
So this is a result we get after the first row operations, right? so we use the third row to minus first row, and then we set the new value to the third row.
01:53
This is negative 1.
01:56
And the next step we do is we continue to label.
01:59
This is row 1, row 2, row 3.
02:03
And this time what we do is we use the we use row 2 or minus 3 times for 1 and we set this new value to row 2.
02:19
After this role operation, what we have is, okay, so this is what we have after this role operation.
02:43
So let's continue to label this row 1, this is row 2, and this is the row 3.
02:48
So next step we want to do.
02:50
Okay, so since now we have.
02:52
You know, successfully turn this two entries into zero.
02:57
So next step we want to do is we want to turn this entries into zero.
03:04
What do we do here? we use row 2 plus 2 and 0 2 times 2 plus row 3 times 5.
03:19
We add this together and we assign this to row 3.
03:24
Okay, so after this row operation, what we have is 1 -191 -90 -5 -4 and 0 -0 -903, negative 3, and 6, negative 23, and here we have 24.
03:48
So notice here, since we only have one entry in this row, okay, negative 3 times this variable, times this variable equals to 24, okay? we can divide negative 3 at this role, and we can change this term into 1, divided by negative 3, okay? so it's become 1, and so this entry, this term becomes negative 8, negative 8, okay? after this rule operation, the next step we want to do is we want to turn this entry, turn this entry into zero.
04:37
Okay, so we're getting closer, closer to the row at the floor, right? so how do we turn this term into zero? this entry into zero...