00:01
Okay, so we're tasked with finding the determinant of this 3x3 matrix.
00:06
And i'm going to use method of minor matrices here and take it from the top row.
00:11
So all we simply do is do one lot of this minor matrix, five lots of this major matrix, and two lots of this minor matrix, and i'll show you here now.
00:20
So if we break this down, we've got one lot of, delete this column this row, minus 7, 8, 9, minus 3.
00:34
And our second one, remember it's a minus for the second bit, minus 5 lots of delete this row, this column, minus 6, 5, 8, minus 3.
00:49
And then finally, we've got 2 lots of minus 6, minus 7, 5.
00:59
And then we need to find a determinant of these 2x2 matrices.
01:02
And to find the determinant of a 2x2 matrix written in this form, we simply do ad minus bc.
01:10
Okay...