September 11 Post

Jessica says:


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"September 11 Post"
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jessica said...
Thank you Reuben for the honor of letting me be the next blogger

Matrix Multiplication patterned examples because this is harder than adding and subtracting and scalar multiplication

A=[a b] [d e]=B
[c d]*[f g]
you end up with:
[AB]=[ad+bf ae+bg]
[cd+df ce+dg]

to put this in numbers:
C=[1 2] [-3 7]=D
[3 4] * [4 2]

[CD]=[(1*-3)+(2*4) (1*7)+(2*2)]
[(3*-3)+(4*4) (3*7)+(4*2)]

[CD]=[5 11]
[-1 29]

To see if a multiplication will work: if the number of columns in the first matrix matches the number of rows in the second matrix, then matrix multiplication is possible

So if Amn * Bpq, then n=p for multiplication to work
so if you have A32 * B26 multiplication will work
but if you have B26 * A32 multiplication will not work because there is a dimensions mismatch

the "Inner Dimensions" say if the multiplication will work and the "Outside Dimensions" say what the new dimensions will be

So in the above case with A32 * B26 multiplication works because the inner dimensions say it does and the new matrix will have dimensions of 3x6

thus ends my very first math blog YAY!
the next blogger will be Ashley for whenever the next class is...have fun!

jessica