00:02
So a multiplication that's undefined would be 3 by 2 times 4 by 1.
00:21
Part b, a is a 3 by 5 matrix.
00:36
What could be the dimensions of b? b would have to be 5 by, it could be 1, 2, 3, so i'm going to say 5 by 2, could be the dimensions.
00:46
For part c, matrix c is 2 by 3.
01:03
D is 2 by 3.
01:10
F is 3 by 2.
01:16
Find the dimensions of cd.
01:21
Well, c times d not defined, as the columns and rows are different.
01:38
So this 3, the 2 by 3, cannot multiply.
01:47
If we multiply, this number would have to be a 3 and it's a 2, 2 by 3.
01:54
So this is the rows by columns.
02:03
These two numbers are different...