Question

Assume X,Y,Z, W and P are matrices of orders $2\times n,3\times k,2\times p,n\times 3andp\times k$ respectivley. Choose the correct answer in Q.21 and Q.22.
If n = p, then the order of the matrix 7X-5Z is
$\left(a\right)p\times 2$
$\left(b\right)2\times 2$
$\left(c\right)n\times 3$
$\left(d\right)p\times n$

Answer 1

Matrix X is of the order $2\times n.$
Therefore, matrix 7X is also of the same order.
Matrix Z is of the order 2 $\times p$ i.e., $2\times n.$ [Since, n=p]
Therefore, matrix 5Z is also of the same order.
Now, both the matrices 7X and 5Z are of the order $2\times n.$
Thus, matrix 7X-5Z is well -defined and is of the order $2\times n.$
So, correct option is (b).