数学题在线解答:三元一次方程组;(1)X+Y+Z=0,4X+2Y+Z=0,Z=2;(2)9X+3Y+Z=0,X-Y+Z=0,Z=-3,
(3)4X+2Y+Z=5,4X-2Y+Z=1Z=-1;(5)5X+2Y+Z=12,4X+3Y+Z=13,Z=3