Question

Assume $X,Y,Z,W$ and $P$ are matrices of order $2\times n,3\times k,2\times p,n\times 3$, and $p\times k$ respectively.
If $n=p$, then the order of the matrix $7X-5Z$ is

• A. $p\times 2$
• B. $2\times n$
• C. $p\times n$
• D. $n\times 3$

Answer 1

The correct option is B $2\times n$

Given:
Order of matrix $X=2\times n$
Order of matrix $7X=2\times p$
Order of matrix $Z=2\times p$
$\therefore$ Order of matrix $5Z=2\times n$
$\because \{n=p\}$
$\therefore$ Order of $7X-5Z=$ Order of $7X$ = Order of $5Z=2\times n$
Hence, correct answer is $B$.