Question 166576
Find the order of the matrix product AB and the product BA, whenever the products exist.
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Rule: The number of columns on the left must be the same as the number
of rows on the right. 
The product of an [x by y matrix] and a [w by z matrix] will be  x by z]
To have a product, y must bethe same as w.
 
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A is 2 x 1, B is 1 x 1 
AB ?
Can be multiplied because 1=1
Product will be 2 x 1
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BA ?
Cannot be multiplied because 1 is not equal to 2
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Answer: a
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Cheers,
Stan H.
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a. AB is 2 x 1, BA is nonexistent.
b. AB is nonexistent, BA is 1 x 2
c. AB is 1 x 2, BA is 1 x 1
d. AB is 2 x 2, BA is 1 x 1