(A,E)= -1 3 -7 10 1 0 0 0 -7 -3 5 10 0 1 0 0 3 1 -1 2 0 0 1 0 1 1 -1 2 0 0 0 1 r1-3r4,r2+3r4,r3-r4 -4 0 -4 4 1 0 0 -3 -4 0 2 16 0 1 0 3 2 0 0 0 0 0 1 -1 1 1 -1 2 0 0 0 1 r1+2r3,r2+2r3,r3*(1/2),r4-r3 0 0 -4 4 1 0 2 -5 0 0 2 16 0 1 2 1 1 0 0 0 0 0 1/2 -1/2