已知：x/3=y/-4=z/7 求3x+y+z/y的值

已知：x/3=y/-4=z/7 求3x+y+z/y的值
已知：x/3=y/-4=z/7 求3x+y+z/y的值

已知：x/3=y/-4=z/7 求3x+y+z/y的值
x/3=y/-4=z/7=k
x=3k y=-4k z=7k
(3x+y+z)/y
=(9k-4k+7k)/(-4k)
=12k/(-4k)
=-3

令a=x/3=y/-4=z/7
x=3a
y=-4a
z=7a
所以原式=(9a-4a+7a)/(-4a)
=12a/(-4a)
=-3