00:01
Given this matrix a, we want to find a squared and a cubed.
00:05
So to find a square, we would have to times a by a.
00:09
So let's do that now as i write out the matrix.
00:13
Okay.
00:13
So when we're multiplying matrices to the same dimensions, you'll end up with the same dimension matrix.
00:18
So we're about 3 by 3 by 3 by 3.
00:20
So we're going to write up with the 3 by 3.
00:21
And if i wanted to find the first, see here, first row, first column, you take the first row from the first matrix and the first column for the second one.
00:30
So you're going to have two lots of two and then you've got multiplied by zeros after, so you've just got a four.
00:35
Equally, if we wanted to do now the second row first column, now you need one to second row, first column, and it's just going to be zero, zero to two, one lot zero, zero to zero.
00:44
And finally, third row, first column is going to be a big fat zero as you've got zero lots of those twos, three lots, zero lots of those threes and zero lots of those twos.
00:53
Okay now, so we're going to be moving on to our second column now, first row.
00:57
Two lots of that minus one is going to give us minus, minus two, minus one lot of that minus one is minus one, plus one lot of that three.
01:04
So we've got minus three plus three.
01:07
That's clearly going to be a zero...