Question

If A is $3\times 4$ matrix and B is a matrix such that A'B and BA' are both defined. Then B is of the type

• A. $3\times 4$
• B. $3\times 3$
• C. $4\times 4$
• D. $4\times 3$

Answer 1

The correct option is A $3\times 4$

$A_{3\times 4}\Rightarrow A_{4\times 3}^{\prime }$Now A'B defined
$\Rightarrow B$is $3\times p$
Again $B_{3\times p}{A}_{4\times 3}^{\prime }$ defined $\Rightarrow p=4$
​$\therefore B$ is $3\times 4$.