已知x,y满足约束条件x-y≥0,x+y≤1,0≤y≤1/2,若目标函数z=ax+y仅在点（1/2,1/2）处取最小值,则实数a的取值范围是

已知实数x,y满足约束条件x+y>3,y 已知变量x,y满足约束条件1 已知x,y满足约束条件1 已知x,y满足约束条件x-y+5>=0 x+y>=0 X 已知x,y满足约束条件：x-y+1>=0,x+y-2>=0,x 已知X,Y满足约束条件x-y+5>=0 x+y>=0 X 设X,Y满足约束条件X+Y 已知x,y满足约束条件x-4y 已知变量x,y满足约束条件｛x+y 已知x,y满足约束条件{x+y+5 已知变量x,y满足约束条件｛x+y x、y满足的约束条件0 已知变量x,y满足约束条件x+2y-3=0,y-1 已知变量x,y满足约束条件x+2y-3=0,y-1 已知x,y满足约束条件x+y==-1,y>=1 若0= 已知xy满足约束条件y=2 2X+y 已知x,y满足约束条件｛x+y+1≤0,x-y+1≥0,y+1≥0,则z=2x-y的最大值是? 已知x y满足约束条件{x≥0 3x＋4y≥4 y≥0 则x＋y＋2x的最小值是多少