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# Math Question Help

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2 Help with this please

Oct 19, 2019

#1
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12  1

-4   1

-11  28

Oct 20, 2019
#2
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For method,

We Multiply first row by first column in the other matrice

E.g,

Let the first matrice be A

and the second be B

A*B=C (Another matrice)

Notice that A is a 3x3 matrice (Because it has 3 rows and 3 columns)

To multiply it by any other matrice it must be 3*x(Where x could be any number >1 of course)

The endings must be the same

for example, 4x4 matrice can only be multiplied by 4*x matrice

Back to the origional question now,

A is 3x3 matrice

B is 3x2 matrice

Both could be multiplied.

A row is the horizontal arrangement of numbers

e.g: 1 3 5 row 1

2 5 7  row 2 etc..

The column is the vertical arrangement of numbers

eg.

col.1 col.2    col.3 and so on.

1        2         5

5        7         4

When we multiply 2 matrices we multiply First row by the column in the second matrice

First row of A * First column of B

so -1*2 + 2*7 + 0*1 (Notice we add them together to just represent 1 number that is written at row 1, column 1) and so on till we do the 3 rows then switch column and redo it :). hope that helps.

Guest Oct 20, 2019