Answer:

Step-by-step explanation:
For two matrix P and Q, the product, say PQ is defined when:
The number of columns of P = The number of rows of Q
Since A is a 2×2 matrix and B is also a 2×2 matrix
Thus both AB and BA are possible.
So AB is:

BA is:

2a + 3b = 6
5a + 2b = 4
We multiply the first equation by 5 and the second by 2 and and subtract the second from the first:
10a + 15b = 30
-10a -4b = -8
11b = 22
b = 2
2a + 3(2) = 6
2a = 0
a = 0
Checking,
5(0) + 2(2) = 4
4 = 4, true