解:2x+4y+3z=9.................(1) 3x-2y+5z=11 ..............(2)5x-6y+7z=13...............(3)(1)+(2)*2:8x+13z=31...................(4)(2)*3-(1):4x+8z=20,x+2z=5....(5)(5)代入(4):8(5-2z)+13z=31-3z=-9z=3x=5-2z=-1y=0.5