Chapter 2.5, Problem 2E

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.

2. $A=\left[\begin{array}{ccc}4& 3& -5\\ -4& -5& 7\\ 8& 6& -8\end{array}\right],b=\left[\begin{array}{c}2\\ -4\\ 6\end{array}\right]$

$A=\left[\begin{array}{ccc}1& 0& 0\\ -1& 1& 0\\ 2& 0& 1\end{array}\right]\left[\begin{array}{ccc}4& 3& -5\\ 0& -2& 2\\ 0& 0& 2\end{array}\right]$