已知x:Y:Z等于3:4:7且2x-y-z=-18求式子x+2y-z的值
问题描述:
已知x:Y:Z等于3:4:7且2x-y-z=-18求式子x+2y-z的值
答
令x=3k,y=4k,z=7k
2x-y-z=-18
2*3k-4k-7k=18
6k-4k-7k=18
5k=-18
k=-18/5
x+2y-z
=3k+2*4k-7k
=3k+8k-7k
=4k
=4*(-18/5)
=-72/5