Show how to find the inverse of the matrix \(B= \left[\begin{array}{cccc} 1 & 3 & 3 & -7 \\ 0 & 1 & 2 & -4 \\ 0 & 0 & 1 & -3 \\ 0 & 3 & 5 & -8 \end{array}\right] \).
Answer:
\[B^{-1}= \left[\begin{array}{cccc} 1 & -15 & 7 & 4 \\ 0 & 7 & -4 & -2 \\ 0 & -9 & 4 & 3 \\ 0 & -3 & 1 & 1 \end{array}\right] \]