Given the matrix $$A=\left[\begin{array}{rr} -2 & 1 \\ 0 & -2 \\ \end{array}\right],$$
find $A^3$. Write $A^3$ as $$A^3=\left[\begin{array}{rrr} a_{11} & a_{12} \\ a_{21} & a_{22} \\ \end{array}\right]$$ input your answer below:
$a_{11}=$
$a_{12}=$
$a_{21}=$
$a_{22}=$