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desalexus
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How can you determine whether a matrix product AB is defined?
 10 months ago
 10 months ago
desalexus Group Title
How can you determine whether a matrix product AB is defined?
 10 months ago
 10 months ago

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Loser66 Group TitleBest ResponseYou've already chosen the best response.0
@Mertsj explain him, please.
 10 months ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.0
You're doing fine. Give an example. That will help.
 10 months ago

desalexus Group TitleBest ResponseYou've already chosen the best response.0
its HER and like this A is 2×3 and B is 3×2, so AB is (2×3)(3×2).
 10 months ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
\[A_{m\times n}B_{n\times p}\]? The number of columns of A = number of rows of B
 10 months ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
Dimension of AB would be m×p
 10 months ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.0
It depends on the dimensions:
 10 months ago

mathmale Group TitleBest ResponseYou've already chosen the best response.0
The example that Desalexus presents is illustrative: A is 2×3 and B is 3×2, so AB is (2×3)(3×2). Note how Matrix A has 2 rows and 3 columns, and B 3 rows and 2 columns. We can indeed multiply matrices A and B (in that order).
 10 months ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.0
dw:1388979444164:dw
 10 months ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.0
dw:1388979475429:dw
 10 months ago

RolyPoly Group TitleBest ResponseYou've already chosen the best response.0
dw:1388979474597:dw
 10 months ago

mathmale Group TitleBest ResponseYou've already chosen the best response.0
Yes, Mertsj, and you can make that statement more precise by stating that "the number of columns of the first matrix must equal the number of rows of the second. RolyPoly is correct in his drawing (immediately above), whereas I found that I was wrong at the onset (and have deleted my incorrect statement accordingly)!
 10 months ago

mathmale Group TitleBest ResponseYou've already chosen the best response.0
I'd rather find my own mistakes than have someone else find them for me! :)
 10 months ago

Mertsj Group TitleBest ResponseYou've already chosen the best response.0
Sometimes it is easier for the asker to see an example than to decipher a bunch or words but it is good to have both so the asker can choose.
 10 months ago
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