Question
Given $\left[\begin{array}{cc}2 & 1 \\ -3 & 4\end{array}\right], X=\left[\begin{array}{l}7 \\ 6\end{array}\right]$ the matrix $X$

Answer

We have
$ \left[\begin{array}{cc} 2 & 1 \\ -3 & 4 \end{array}\right], X =\left[\begin{array}{l} 7 \\ 6 \end{array}\right]$ Let $X =\left[\begin{array}{l}x \\ y\end{array}\right]$
So, $\left[\begin{array}{cc}2 & 1 \\ -3 & 4\end{array}\right]\left[\begin{array}{l}x \\ y\end{array}\right]=\left[\begin{array}{l}7 \\ 6\end{array}\right]$
$ \Rightarrow\left[\begin{array}{c} 2 x+y \\ -3 x+4 y \end{array}\right]=\left[\begin{array}{l} 7 \\ 6 \end{array}\right] $
Multiplying $(i)$ by $3$ and $(ii)$ by $2,$ and adding we get:
$6 x+33 y=21$
$ -6 x+8 y=12$
$ 11 y=33$
$ \Rightarrow y =3$
From $(i),$
$2 x=7-3=4$
$ \Rightarrow x=2$
So, $X=\left[\begin{array}{l}2 \\ 2\end{array}\right]$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free