(1)×2-(2)得4x-3y=5 (4)(1)×3+(3)得10x-3y=17 (5)(5)-(4)得6x=12∴x=2把x=2代入(4)得8-3y=5∴y=1把x=2,y=1代入(1)得6-2+Z=7∴z=3