% Linear Algebra: Theory and Applications 
% Ward Cheney & David Kincaid 
% JBPub.com (c) 2008 
% File: exp128.m
% Example 1.2.8      

A = [1,2,3,20; 4,5,6,47; 7,8,9,74; 10,11,12,101]
rref(A)