设实数x,y满足x^2+y^2+8x+6y+25=0,求(x^2-4y^2)/(x^2+4xy+4y^2)-x/x+2y的值．

设实数x,y满足 x>=0 x-2y>=0 x-y-2 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2x^2+3y^2=6y,求x+y的最大值 设实数x、y满足方程2x²+3y²=6y,求x+y的最大值 设实数x,y满足x^2+y^2+8x+6y+25=0,求(x^2-4y^2)/(x^2+4xy+4y^2)-x/x+2y的值． 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= 设正实数x,y满足x^3+y^3=x-y,求证：x^2+4y^2 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x的平方+4y的平方+2x 设实数x,y满足方程组①x-y-2=0 ③2y-3 设实数x,y满足方程：x^+y^-8x-6y+21=0,求：（1）2x-y的取值范围 （2）x^+y^-10x+2y+26的取值范围,设实数x,y满足方程：x^+y^-8x-6y+21=0,求：（1）2x-y的取值范围 （2）x^+y^-10x+2y+26的取值范围, 设实数x、y满足方程2x2+3y2=6y,则x+y的最大值 设实数x,y满足3 设实数x,y满足3 设实数x,y满足0 不等式：设实数x,y满足3