已知：xx+yy-8x+12y+52=0,求：x/y-y/x=多少

已知：xx+yy-8x+12y+52=0,求：x/y-y/x=多少 已知xx+yy+4x-6y+13=0,求（xx-2x）/xx+3yy的值. 已知2x=3y,求xy/xx+yy-yy/xx-yy的值 已知XX+YY+4X-6Y+13=0,则X的Y次方是 (x-y)(x+y)(xx-yy)=? xx+2x+yy+6y+10=0求xx+yy的值 x>0,y>0,x+y=1求1/(xx)+8/(yy)最小值x>0,y>0,x+y=1,求1/(xx)+8/(yy)最小值 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 已知实数x,y满足xx+yy-2x=0,则2xx+yy的取值范围是why 已知x+y=7,xy=-8,求xx+yy 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x,y是实数,且适合方程(xx+xy-12)(xx+xy-12)+(xy-2yy-1)(xy-2yy-1)=0求x,y的值 xx+12*12=yy(y-x=2) 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 已知x-y=2,（xx）-（yy）=12,求x与y的值 已知xx+yy-4x-6y+13=0求3x+4y的值