Question

If $\left[\begin{array}{cc}3& -1\\ 0& 6\end{array}\right]\left[\begin{array}{c}3x\\ 1\end{array}\right]+\left[\begin{array}{c}-2x\\ 3\end{array}\right]=\left[\begin{array}{c}8\\ 9\end{array}\right]$ the value of $x$ is

• A. $7$
• B. $-\frac{2}{9}$
• C. $-\frac{3}{8}$
• D. None of the options

Answer 1

The correct option is D None of the options

$\left[\begin{array}{c}9x-1\\ 6\end{array}\right]+\left[\begin{array}{c}-2x\\ 3\end{array}\right]=\left[\begin{array}{c}8\\ 9\end{array}\right]$

$\Rightarrow \left[\begin{array}{c}9x-1-2x\\ 6+3\end{array}\right]=\left[\begin{array}{c}8\\ 9\end{array}\right]$

$\Rightarrow \left[\begin{array}{c}7x-1\\ 9\end{array}\right]=\left[\begin{array}{c}8\\ 9\end{array}\right]$
$\Rightarrow 7x-1=8\Rightarrow x=\frac{9}{7}$