Question

# Give an example of an upper triangular matrix.

An upper triangular matrix is a triangular matrix with all elements equal to below the main diagonal. It is a square matrix with element ${{\text{a}}_{{\text{ij}}}}$ where ${{\text{a}}_{{\text{ij}}}}$ = 0 for all j < i.
Example of a $2 \times 2$matrix.
$\left( {\begin{array}{*{20}{c}} 1&2 \\ 0&3 \end{array}} \right)$
Example of a $3 \times 3$matrix
$\left( {\begin{array}{*{20}{c}} 8&9&7 \\ 0&7&5 \\ 0&0&4 \end{array}} \right)$