Chapter 2.5, Problem 1E

In Exercises 1–6, solve the equation Ax = b by using the LU factorization given for A. In Exercises 1 and 2, also solve Ax = b by ordinary row reduction.

1. $A=\left[\begin{array}{ccc}3& -7& -2\\ -3& 5& 1\\ 6& -4& 0\end{array}\right],b\text{ = }\left[\begin{array}{c}-7\\ 5\\ 2\end{array}\right]$

$A=\left[\begin{array}{ccc}1& 0& 0\\ -1& 1& 0\\ 2& -5& 1\end{array}\right]\left[\begin{array}{ccc}3& -7& -2\\ 0& -2& -1\\ 0& 0& -1\end{array}\right]$