00:01
Given this matrix a, we're asked to find the values lambda such that the matrix a minus lambda i is not invertible.
00:09
And i just want to mention that a matrix is not invertible if and only if its determinant is equal to zero.
00:15
So we're going to find those values lambda by using the determinant.
00:21
Right.
00:21
So we're going to calculate a minus lambda i.
00:26
Ok, so i'm going to use serris's rule and write the first and second columns here.
00:33
Ok, so first i have the product of these three entries.
00:41
So i have four minus lambda times the quantity six minus lambda times the quantity three minus lambda.
00:53
And then this entry is zero because of zero.
00:58
And then similarly, this entry is also zero.
01:04
And then i have minus this entry, which is zero.
01:12
And this this entry, which is also zero...