00:01
For this exercise, we have the determinant, lambda 0, 0 lambda, and subtract that from the matrix 2, 1, 1, 2.
00:20
And that's the determinant.
00:21
It's going to be lambda minus 2, negative 1, negative 1, lambda minus 2, which equals lambda squared minus 4 lambda plus 3.
00:32
So here we get that lambda sub 1 equals 3 and lambda sub 2 equals 1.
00:46
And we have the determinant of 2, 1, 1, 2 is equal to 3, which is greater than 0.
00:54
So this is positive definite.
00:59
That's a...