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Matrices

Vgbg
(edited 7 years ago)
Matrices Q15.png90.1KB
In order for a Matrix multiplication to be allowed... the number of columns in the first matrix must be equal to the number of rows in the second matrix. :smile:
AxB
BxC
CxA
CxB

just set out the matrices as 2x2 for A, 2x3 for B, 3x2 for C.
then put them next to each other e.g. AB (2x2 2x3), the middle numbers are both 2 so it means it would work.
another one for example is BC (2x3 3x2) both middle numbers are 3.
Try it for CxA and CxB
(edited 7 years ago)
Original post by Deeboss
Matrices Q15.png

Q15

Could some please explain this to me. I am having a hard time learning matrices. How am I mean to work this out?


Matrices are kewl.

It would help to write down the dimensions of each matrix; number of rows, by number of columns.
B would be (2x3)

AB - To multiply matrices together, the number of columns of Matrix A needs to be equal to the number of rows of matrix B

This also determines the dimensions of matrix AB. Number of rows of matrix A, number of columns of matrix B

If you need anything else.
I don't even talk to the guy but @RDKGames is a lad. Always happy to help.
(edited 7 years ago)
Original post by robinhood111
AxB
BxC
CxA
CxB


M8 ur sik @ explaining tings.
hope it helps, thats the easiest way i could think of
Reply 6
Avatar for Deeboss
Deeboss
OP
11
Original post by Maths is Life
Matrices are kewl.

It would help to write down the dimensions of each matrix; number of rows, by number of columns.
B would be (2x3)

AB - To multiply matrices together, the number of columns of Matrix A needs to be equal to the number of rows of matrix B

This also determines the dimensions of matrix AB. Number of rows of matrix A, number of columns of matrix B

If you need anything else.
I don't even talk to the guy but @RDKGames is a lad. Always happy to help.


Why would the answer not be AxC or BxA?
Original post by Deeboss


Q15

Could some please explain this to me. I am having a hard time learning matrices. How am I mean to work this out?


For an arbitrary matrix of size Mi×jM_{i\times j} where the number of rows is denoted by ii and the number of columns denoted by jj, the product of two matrices, Ma×bMc×dM_{a \times b}M_{c \times d}, is only valid when b=cb=c

So you can denote matrix sizes:
A=M2×2A=M_{2\times 2}
B=M2×3B=M_{2\times 3}
C=M3×2C=M_{3\times 2}

then see for which product combinations of two matrices the rule holds.

If you want to see why it is so, simply attempt to multiply out an option which is against the rule.
(edited 7 years ago)

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