Question

Please help!
Matrix Pre-calc

Answer 1

M+N is defined

All others not defined

Explanation:

Two matrices can be added or subtracted if and only if they have the same dimensions i.e. they must have the exact same number of rows and number of columns

Only M and N with dimensions (4 x 2) each can be added or subtracted.

(4 x 2 ) means 4 rows and 2 columns

So the only defined operation is
M + N

All the others are not defined

Answer 2

`\textsf{De\:\!fined}: \quad \boxed{M + N}`

`\textsf{Not\:de\:\!fined}: \quad \boxed{N - Q} \quad \boxed{Q + L} \quad \boxed{M - P}`

Explanation:

Generally, a matrix is referred to as
`n* m` where n is the number of rows and m is the number of columns.

Therefore:

• L is a 2 x 2 matrix
• M is a 4 x 2 matrix
• N is a 4 x 2 matrix
• P is a 2 x 2 matrix
• Q is a 2 x 1 matrix

Matrices can be added or subtracted only when they are the same size.

`\boxed{N - Q}`

Matrices N and Q are different sizes. Therefore, the operation is not defined.

`\boxed{M + N}`

Matrices M and N are the same size. Therefore, the operation is defined.

`\boxed{Q + L}`

Matrices Q and L are different sizes. Therefore, the operation is not defined.

`\boxed{M - P}`

Matrices M and P are different sizes. Therefore, the operation is not defined.