设变量x,y满足x+y

设变量x,y满足约束条件x-y>-1,x+y>1,3x-y 设z=2x+y式中变量x,y同时满足x-4y 设变量X,Y满足约束条件{X-Y+3>=0,X+Y>=0,-2 已知变量X.Y满足 设变量xy满足 x+y-3 x-y+1 3x-y+5 z=x+y/x 设变量x,y满足约束条件x-y>=-1,x+y>=1,3x-y 设变量x，y满足约束条件x−y≥0x+y≤1x+2y≥1 设变量x，y满足约束条件x+y≤3x−y≥−1y≥1 设变量x y满足约束条件x-y≥-1 x+y≥1 2x-y≤1 z=(x-2y)/(x+y)的最大值 变量x,y满足x-2y=0,x 设变量x，y满足|x|+|y|≤1，则x+2y的最大值和最小值分别为（　　） 设X,Y满足约束条件X+Y