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Question
Compute the products AB and BA whichever exists in each of the following cases:
`A= [[1 -2],[2 3]]` and B=`[[1 2 3],[2 3 1]]`
Solution
`AB=[[1 -2],[2 3]][[1 2 3],[2 3 1]]`
`⇒AB=[[1-4 2-6 3-2 ],[2+6 4+9 6+3]]`
`⇒AB = [[-3 -4 1],[8 13 9]]`
Since the number of columns in B is greater then the number of rows in A, BA does not exists.
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