Question

Use suitable transformation on $\left[\begin{array}{cc}1& 2\\ 3& 4\end{array}\right]$ to convert into an upper triangular matrix.

Answer 1

$\left[\begin{array}{cc}1& 2\\ 3& 4\end{array}\right]$

$\Rightarrow R2\to R2-3$

$\Rightarrow \left[\begin{array}{cc}1& 2\\ 0& 1\end{array}\right]$ is an upper triangular matrix.