Question

If $\left[\begin{array}{cc}x& 4\\ 5& y\end{array}\right]$+$\left[\begin{array}{cc}-2& 1\\ 1& 2\end{array}\right]$=$\left[\begin{array}{cc}0& 5\\ 6& 0\end{array}\right]$, then $x-y=$

• A. 0
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (D)

We have,

$\left[\begin{array}{cc}x& 4\\ 5& y\end{array}\right]$+$\left[\begin{array}{cc}-2& 1\\ 1& 2\end{array}\right]$=$\left[\begin{array}{cc}0& 5\\ 6& 0\end{array}\right]$,

$\Rightarrow \left[\begin{array}{cc}x-2& 4+1\\ 5+1& y+0\end{array}\right]$ $=\left[\begin{array}{cc}0& 5\\ 6& 0\end{array}\right]$,

On comparing, we get

$x-2=0$ and $y+2=0$

$\Rightarrow x=2$ and $y=-2$

$\therefore x-y=2-(-2)$

$\Rightarrow x-y=4$