已知X:Y:Z=3:4:7且2X-Y+Z=-18求式子X+2Y-Z的值

来源:学生作业帮助网 编辑:作业帮 时间:2021/08/06 00:30:09

已知X:Y:Z=3:4:7且2X-Y+Z=-18求式子X+2Y-Z的值
已知X:Y:Z=3:4:7且2X-Y+Z=-18求式子X+2Y-Z的值

已知X:Y:Z=3:4:7且2X-Y+Z=-18求式子X+2Y-Z的值
因为 x :y :z = 3 :4 :7
所以设 x = 3k ,y = 4k ,z = 7k
因为 2x - y + z = -18
所以 6k - 4k + 7k = -18
k = -2
x + 2y - z
= 3k + 8k - 7k
= 4k
= -8

x=-6
y=-8
z=-14
x+2y-z=-8