解: 增广矩阵 =2 1 -1 1 14 2 -3 1 32 1 -3 -1 3r2-2r1, r3-r12 1 -1 1 10 0 -1 -1 10 0 -2 -2 2r1+r2, r3-2r2, r2*(-1)2 1 0 2 00 0 1 1 -10 0 0 0 0选 x1,x4 为自由未知量通解为: (0,0,-1,0)+c1(1,-2,0,0)+c2(0, 2, 1,-1).