00:01
Okay, we want to prove that the matrix d times the identity is equal to the identity times by d.
00:06
And whenever you times anything by identity always comes out itself, no matter which way around you do it, i promise you that, but we'll show you that here.
00:12
When we're doing matrix multiplication, we do the rows of the first matrix against the columns of the second one.
00:19
So for the first row, first column position, you do the first row against the first column.
00:22
So you'll have one times one, two zero, three zero, so we just have one there.
00:26
For the first row, second column, one, two, three against zero one, zero, so zero times one, two, one times two, and zero times three.
00:36
And then for the third and final column of the first row, we're just going to have one times three...