00:01
So here we're given the matrices, a, b, and c.
00:04
A is a 2 by 3.
00:06
B is a 2 by 2 and 2 and c is a 3 by 2 matrix.
00:11
Then for part a, we want to evaluate 3a minus 4c transpose.
00:19
Well, let's see 3a is going to be 15, 3, 6, 12, 9, negative 3, c transpose.
00:31
Is going to be 1 .5, 2 .0, 0, 5.
00:41
And 4c transpose is going to be 4 -8, 12, negative 12, 0, 20.
00:52
So then 3a minus 4c transpose is going to be 15 minus 4x4, 3 minus 8, 6 minus 12, 6 minus 12, 12 minus negative 12, 9 minus 0 and negative 3 minus 20.
01:15
And then let's see here.
01:24
For b, we want to explain why a, b cannot be evaluated.
01:30
Well, a is a 2 by 3.
01:33
B is a 2 by 2.
01:36
And since these 3 is not equal to 2, we cannot evaluate.
01:49
B since the number of columns in a is not equal to the number of rows in b.
02:07
And for part c, evaluate b, a.
02:16
Well, that is going to be 1 -6 -5 -4 times 5 -4, 5 -2, 4, 3.
02:27
Negative 1.
02:29
So you take the rows of b multiply them by the columns of a and you're going to get, let's see this is a 2 by 2, this is a 2 by 3.
02:39
So you're going to end up with a 2 by 3.
02:45
And this is going to be 5 plus 6 times 4 is 24.
02:52
This is 29.
02:55
Then 1 times 1 plus 6 times 3 is 19, 1 times 12 plus 6.
03:03
Oh, this should, let's see here.
03:06
This is not 12.
03:08
This one is over here.
03:10
So 2 minus 6 is negative 4...