00:03
All right, they want us to find the determinant of a by expanding on this first column.
00:09
So to do that, we take the three things that are in the first column.
00:15
We have one, zero, and zero.
00:22
And now we need their co -factors.
00:24
In this case, we need negative one.
00:30
And then the row plus the column that it's in.
00:33
One is in the first row, first column.
00:35
So we have an expert of two.
00:36
We want things that are not in the same row or column.
00:40
That's these four things.
00:43
2, negative 3, negative 1.
00:48
And now the good part about picking column 1 is that i'm going to get 0 for the next two terms...