MCQ
If $\text{A} =\displaystyle \begin{bmatrix} -1 &\text{amp; } 0 &\text{amp; }0 \\ 0 &\text{amp; }\text{x} &\text{amp; } 0 \\ 0 &\text{amp; } 0 &\text{amp; }\text{m} \end{bmatrix}$is a scalar matrix then $\text{x}+\text{m}=$
  • A
    0
  • B
    -1
  • -2
  • D
    -3

Answer

Correct option: C.
-2
A scalar matrix has all the elements of the diagonals same.For example:$ \begin{bmatrix} 3 &\text{amp; } 0\\ 0&\text{amp; } 3 \end{bmatrix}$

In our case A is given to be a scalar matrix hence all the diagonal elements must be same.

So, $\text{x} = \text{m} = -1$

And $\text{x}+\text{m} = -1 -1 = -2$

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