|x|+|y|≤1 求z=x-y+2的取值范围

已知||x|-|y||≤1,z=x^2+y^2-6x-2y+10,求z的取值范围? 设变量x,y满足约束条件{x-y≥0,x+y≤1 x+2y≥1 求z=y/x+1的取值范围 z=(x-1/2)^2+y^ 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 设实数x,y满足{x-y-2≤0 x+2y-5≥0 y-2≤0.（1）求z=x+y的取值范围；（2）求u=（x+y）/x 设实数x,y满足{x-y-2≤0,x+2y-5≥0,y-2≤0.求z=x+y和z=x+y/x的取值范围 1.x+y+z=30,3x+y-z=50,x,y,z为非负数,求5x+4y+2z取值范围. 已知实数 X小于等于Y小于等于Z,且满足:3Y+2Z=3+X,3Y+Z=4-3X,(1)求X的取值范围;(2)求X+Y+ 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. 若x,y,z都是正数,且3x+2y-z=4,求x+y+z的取值范围. 满足约束条件x-y≥-1,x+y≤3且x、y非负的Z=x-2y的取值范围? 已知实数x,y,z满足以下条件,求x的取值范围.x+y+z=a,x2+y2+z2=1/2 a2 ｛1≤x+y≤3 已知 {-1≤x-y≤1求Z＝4x+2y的取值范围