with(LinearAlgebra):A:=<<-1,1,-1>|<-1,-1,1>|<0,-1,2>|<0,0,-1>|<M,1,0>|<M,0,1>|<0,1,1>>;#Step one: Row reduce to get rid of M in first row.
A1:=RowOperation(A,[1,2],-M):
A2:=RowOperation(A1,[1,3],-M);# Pivot in Column 3, Row 3 (counting first row as Row 1)A3:=RowOperation(A2,3,1/2):
A4:=RowOperation(A3,[1,3],M):
A5:=RowOperation(A4,[2,3],1);# Pivot in Column 1, Row 2:
A6:=RowOperation(A5,2,2):
A7:=RowOperation(A6,[1,2],1+1/2*M):
A8:=RowOperation(A7,[3,2],1/2);# We have a feasible solution, but cannot pivot any further...