00:01
The topic of this question is eigenvalues and eigenvectors.
00:06
This question asks us to show that for a 2x2 matrix a, the characteristic equation can be written in this form, where tr of a represents the sum of the diagonal entries of a called the trace of a, and debt of a represents the determinant of a.
00:28
So let's write down some general 2x2 matrix a, call its entries a, b, c, and d.
00:46
So since the trace of a is the sum of the diagonal entries, we can simply say trace of a equals a plus d.
00:59
The determinant of a is defined for a 2x2 matrix as the product of the main diagonal.
01:09
Entries, minus the product of the other entries.
01:20
So now we know what we have to prove for this matrix a, specifically, lambda squared, or that the characteristic equation is lambda squared minus a plus d times lambda plus ad minus b c...