已知X:y:Z=3:4:7,且2X-Y+Z=-18 求X+Y+Z的值

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已知X:y:Z=3:4:7,且2X-Y+Z=-18求X+Y+Z的值已知X:y:Z=3:4:7,且2X-Y+Z=-18求X+Y+Z的值已知X:y:Z=3:4:7,且2X-Y+Z=-18求X+Y+Z的值设

已知X:y:Z=3:4:7,且2X-Y+Z=-18 求X+Y+Z的值
已知X:y:Z=3:4:7,且2X-Y+Z=-18 求X+Y+Z的值

已知X:y:Z=3:4:7,且2X-Y+Z=-18 求X+Y+Z的值
设:X=3t Y=4t Z=7t
所以:6t-4t+7t=-18
t=-2
X=-6 Y=-8 Z=-14

解得x=-6 y=-8 z=-14
则x+y+z=-28

设:X=3C Y=4C Z=7C 则6C-4C+7C=-18 C=-2
X=-6 Y=-8 Z=-14 X+Y+Z=-28