00:01
For this problem, we have been given a matrix multiplication problem consisting of three diagonal matrices.
00:08
And we're supposed to find the product by inspection.
00:11
When we multiply diagonal matrices together, our result is also a diagonal matrix.
00:17
So i'm going to have a diagonal matrix, meaning that i'm going to have zeros everywhere except on that diagonal.
00:26
So i need to find my diagonal entries.
00:28
Now, when i multiply diagonal matrices, let's look at the first two here.
00:33
When i multiply across the first row and down the first column, those first elements in my diagonals will get multiplied together, everything else is going to be zero when i multiply across and down.
00:46
So i'm just going to have that diagonal piece.
00:48
And i'm going to have that all the way across...