Question

If $\left[\begin{array}{ccc}x+3& z+4& 2y-7\\ -6& a-1& 0\\ b-3& -21& 0\end{array}\right]=\left[\begin{array}{ccc}0& 6& 3y-2\\ -6& -3& 2c+2\\ 2b+4& -21& 0\end{array}\right]$, then the value of $a$ is:

• A. $-1$
• B. $-2$
• C. $1$
• D. $2$

Answer 1

The correct option is B $-2$

As the given matrices are equal , therefore, their corresponding elements must be equal. Comparing the element $a_{22}$ of both matrices, we get
$a-1=-3,$
$\Rightarrow a=-2$