方程组{x+y+z=15 x+5y+10z=70（得数只能取非负数）怎么解

1.x+y+z=30,3x+y-z=50,x,y,z为非负数,求5x+4y+2z取值范围. 解方程组x+y-z=-5,x-y-z=1,x-y+z=15 方程组x-y-z=5 y-x-z=1 z-x-y=-15的解是? 若x+y+z=30，3x+y-z=50，x、y、z皆为非负数，求M=5x+4y+2z的取值范围． 若X+Y+Z=30,3X+Y-Z=50,X,Y,Z均为非负数,求M=5X+4Y+2Z,m的取值范围. 已知x,y,z为非负数,且3x+2y+z=5,2x+y-3z=1.若S=3x-y-7z,试求S的取值范围 若2x+y-3z=1,3x+2y+z=5,x、y、z都是非负数,设m=3x+y-7z,求m的取值范围. 已知x+y+z=30,3x+y-z+50,x.y.z皆为非负数,求m=5x+4y+2z的取值范围. 若x,y,z,满足3x+2y+z=5,2x+y-3z=1.y是非负数.求z的取值范围 c语言中负数的非等于多少?intx,y,z且x=3,y=-4,z=5求!（x>y)+(y!=z)或（x+y）与（y-z) 解方程组{x(x+y+z)=6,y(x+y+z)=12,z(x+y+z)=18 解3元一次方程组：x+y+z=70 x/30+y/20+z/40=2/5 x/40+y/20+z/30=10/23