c = [ -4 -3 0 0 0 ]' ;
b = [ 30 6 50 ]' ;
A = [ 2   3   1   0   0  
      1   0   0   1   0  
      6   4   0   0   1 ];
bix = [3 4 5];
zcheat = -36;
xcheat = [3 8 0 3 0]';

