解齐次线性方程组，x1+x2-x3-x4=0,2x1-5x2+3x3+2x4=0,7x1-7x2+3x3+x4=0，线性代数的题

1. 解: 系数矩阵 = 1 1 -1 -1 2 -5 3 2 7 -7 3 1 r2-2r1, r3-7r1 1 1 -1 -1 0 -7 5 4 0 -14 10 8 r3-2r2 1 1 -1 -1 0 -7 5 4 0 0 0 0 r2*(-1/7) 1 1 -1 -1 0 1 -5/7 -4/7 0 0 0 0 r1-r2 1 0 -2/7 -3/7