2 1 -1 -1 3 -3 -1 5 1 -2 3 6 0 5 -8 -13 0 3 -10 -13 1 -2 3 6 then switch rows 1 -2 3 6 0 5 -8 -13 0 3 -10 -13 1 -2 3 6 0 15 -24 -29 0 15 -50 -65 E3-E3-E2; E2+8E3 and E1-3E3 1 -2 0 3 0 5 0 -5 0 0 1 1 1 -2 0 3 0 1 0 -1 0 0 1 1 then E1=E1+2E2 1 0 0 1 0 1 0 -1 0 0 1 1