解消元5x+4y+z=0.1)3x+y-4z=11.2)3+y+z=0.3)1)*3-2)*5:12y+3z-5y+20z=-55,7y+23z=-55.4)4)-3)*7:16z=21-55=-34,z=-34/16=-17/8y=-3-z=-41/85x=17/8+164/8=191/8x=191/40