Subtracting matrices is undefined

[frctl]

I have to perform the following matrix operation:
2B - C

The matrices are:

and

2B is
8 -2
0 4

- C is
...

Is the subtracting not possible
therefore the system is undefined?

 

[pka]

I have to perform the following matrix operation:
2B - C
The matrices are:
View attachment 13462 and View attachment 13463
Is the subtracting not possible
therefore the system is undefined?

Two matrices can be added/subtracted only if they have the same dominions.
\(\displaystyle M_{j\times k}\pm N_{j\times k}\)

 

[HallsofIvy]

Your title really got me started! "Where did you get the idea that subtraction of matrices is undefined?!"

Of course, that is not what you are saying. Addition and subtraction of matrices are only defined for matrices with the same number of rows and columns. Here 2B is a 2 by 2 matrix and C is a 2 by 3 matrix so 2B- C is not defined in this case.

(But -C is defined it is \(\displaystyle \begin{bmatrix}-1 & -4 & -2 \\ -3 & -1 & -5 \end{bmatrix}\).)

 

[frctl]

ok thanks for helping notice this

 

[Steven G]

Even if subtraction of matrices were not defined, then A-B= A+(-1*B) and you have a sum!