Posted by **Ray Scholz** on Wednesday, January 26, 2011 at 2:27pm.

Could someone check this matrix calculation

The first matrix dimension is 1 by 3

row 1 = 1

row 2 = 7

row 3 =3

Second matrix is 1 by 3

Row 1 column one =2

row 1 column two = -5

row one column three = 5

my calculation is that it would be the dimensions of 3 by 3

Final calcs would be row 1 column 1 = 2

row one-column two = -1

row one column three = 5

row two column 1 = 14

row two column two= -7

row two column three = 35

row three column one = 6

row three column two = -3

row three column three = 15

Is that correct?

- Algebra II-Please check calcs -
**Reiny**, Wednesday, January 26, 2011 at 2:42pm
when you describe the first matrix as

row 1 = 1

row 2 = 7

row 3 =3

you are describing a column matrix with dimension 3 by 1 , not 1 by 3

so I see you multiplying

1

7

3

by

2 -5 5

I got

2 -5 5

14 -35 35

6 -15 15

I am used to this notation :

m by n matix has m rows and n columns

Are you not using that same notation?

anyway, you could not multiply a 1by3 by a 1by3, no matter what notation you are used to

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