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的取值范围.

设实数x,y满足 x>=0 x-2y>=0 x-y-2 设实数X,Y满足2X+Y-2>=0,X-2Y+4>=0,3X-Y 设实数x,y 满足x²+4y²+2x-4y+2+0 则x+y= 设Z=x+y,其中实数x,y满足不等式x+2y>=0,x-y 设z=x+y,其中实数x,y满足{x+2y>=0,x-y 设实数x,y满足约束条件：x>=2;y>=x;2x+y 设实数x,y满足方程组①x-y-2=0 ③2y-3 设实数x,y满足0 设实数x,y满足x-y-2≥0,x+2y-4≥0,2y-3≤0(1)2x+y的最小值为 设实数x,y满足y+x^2=0,0 设实数x.y满足y+x^2=0,若0 ·设实数x,y满足y+x^2=0,若0 设实数x,y满足y+x^2=0,0 设实数x.y满足x^2+y=0(0 设实数x,y满足y+x^2=0,0 设实数x,y满足2x+y≤4,x-y≥-1,x-2y≤2,则z=x+y的最大值为 设正实数x,y满足x^3+y^3=x-y,求证：x^2+4y^2 设实数x,y满足x的平方+4y的平方+2x