已知 xx-2x+yy+6y+10=0 求x+y的值快点．快点．急求．

已知xx+yy+4x-6y+13=0,求（xx-2x）/xx+3yy的值. xx+2x+yy+6y+10=0求xx+yy的值 已知2x=3y,求xy/xx+yy-yy/xx-yy的值 若xx+yy-2x-6y+10=0,求分式（xx-yy）/xy的值. 已知xx yy 2x-6y 10=0求x,y的值已知xx+yy+2x-6y+10=0求x,y的值 若xx-2x+yy+6y+10=0 求xx-yyy的值 若xx-2x+yy+6y+10=0 求xx-yyy的值 已知XX+YY+4X-6Y+13=0,则X的Y次方是 已知x(x-1)-(xx-y)=-3求xx+yy-2xy 已知x（x+1)-(xx+y)=3,求(xx+yy)/2-xy的值 已知 xx-2x+yy+6y+10=0 求x+y的值快点．快点．急求． 已知实数x,y满足xx+yy-2x=0,则2xx+yy的取值范围是why 已知xx+yy-4x-6y+13=0求3x+4y的值 已知14(XX+YY+ZZ)=(X+2Y+3Z)^2,求X:Y:Z (x-y)(x+y)(xx-yy)=? matlab程序如下：为什么提示运行出错?x= 0:0.01:20;y= 0:0.01:15;[xx,yy]=meshgrid(x,y,'r');q1=1./((yy-10).^2+(xx-4).^2+9);q2=1./((yy-10).^2+(xx-8).^2+9);q3=1./((yy-10).^2+(xx-12).^2+9);q4=1./((yy-10).^2+(xx-16).^2+9);q5=1./((yy-5).^2+(xx-4) 一下matlab程序运行有误,请问哪里有错,x= 0:0.01:20;y= 0:0.01:15;[xx,yy]=meshgrid(x,y,'r');q1=1./((yy-10).^2+(xx-4).^2+9);q2=1./((yy-10).^2+(xx-8).^2+9);q3=1./((yy-10).^2+(xx-12).^2+9);q4=1./((yy-10).^2+(xx-16).^2+9);q5=1./((yy-5).^2+(xx-4 已知（x-2）2+1y-31=0,求xx+yy-xy-yx的值.