Show how to find the inverse of the matrix \(A= \left[\begin{array}{cccc} 1 & -1 & 3 & 5 \\ 0 & 1 & -5 & -8 \\ 0 & 0 & 1 & 2 \\ 0 & 1 & -3 & -3 \end{array}\right] \).
Answer:
\[A^{-1}= \left[\begin{array}{cccc} 1 & 2 & 4 & -1 \\ 0 & 3 & 9 & -2 \\ 0 & 2 & 5 & -2 \\ 0 & -1 & -2 & 1 \end{array}\right] \]