Question

What is the output order for the following matrix multiplication $A_{2\times 1}\times B_{1\times 2}$?

• A. $1\times 1$
• B. $2\times 3$
• C. $2\times 2$
• D. $2\times 1$

Answer 1

The correct option is C $2\times 2$

We know that $m\times n$ is the order of matrix $AB$ if the order of matrix $A$ is $m\times p$ and the order of $B$ is $p\times n.$

Since, $A$ is of size $2\times 1$, and $B$ is of size $1\times 2$, in which case the output is of size $2\times 2$

and is the matrix product of $A$ and $B$.