Question
if $A=\left[\begin{array}{ll}1 & 2 \\ 3 & 4\end{array}\right]$ and $X$ is a $2 \times 2$ matrix such that $A X=1$, then find $X$.

Answer

We will reduce the matrix $A$ to the identity matrix by using row transformations. During this proccess, I will be converted to the matrix $X.$
We have $AX = I.$
$\therefore\left[\begin{array}{ll}1 & 2 \\ 3 & 4\end{array}\right] X=\left[\begin{array}{ll}1 & 0 \\ 0 & 1\end{array}\right]$By $R_2-3 R_1$, we get,
$\left[\begin{array}{rr}1 & 2 \\0 & -2\end{array}\right] X=\left[\begin{array}{rr}1 & 0 \\-3 & 1\end{array}\right]$
By $\left(-\frac{1}{2}\right) R_2$, we get,
$\left[\begin{array}{ll}1 & 2 \\0 & 1\end{array}\right] X=\left[\begin{array}{rr}1 & 0 \\\frac{3}{2} & -\frac{1}{2}\end{array}\right]$
By $R_1-2 R_2$, we get, Maharash
$\begin{array}{l}{\left[\begin{array}{ll}1 & 0 \\0 & 1\end{array}\right]X=\left[\begin{array}{rr}-2 & 1 \\\frac{3}{2} & -\frac{1}{2}\end{array}\right]} \\ \therefore X=\left[\begin{array}{rr}-2 & 1 \\\frac{3}{2} & -\frac{1}{2}\end{array}\right]\end{array}$

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