Question

if $A = \begin{bmatrix}2&1\\ -1&2\end{bmatrix}, B = \begin{bmatrix}1&-2\\ 2&1\end{bmatrix}, C = \begin{bmatrix}1&-3\\ 2&1\end{bmatrix},$ then

• A. $A + B = B + A$ and $A + (B + C) = (A + B) + C $
• B. $A+ B = B +A$ and $AC = BC $
• C. $A + B = B + A$ and $AB = BC $
• D. $AC = BC$ and $A = BC$

Answer 1

Answer: (A)

In option (a), there are two laws, commutative law and associative law, which are satisfied by all matrices. Thus, option (a) is correct.