解: 增广矩阵=1 -1 1 -1 11 -1 -1 1 01 -1 -2 2 -1/2r2-r1,r3-r11 -1 1 -1 10 0 -2 2 -10 0 -3 3 -3/2r2*(-1/2), r1-r2,r3+3r21 -1 0 0 1/20 0 1 -1 1/20 0 0 0 0方程组的一般解为: (1/2,0,1/2,0)'+c1(1,1,0,0)'+c2(0,0,1,1)'.