已知x^2+y^2+4x+20-8y=0

已知x^2+4y^2-4x+8y+8=0,求x+y 已知方程组4x+2y=1,20x+8y,求x,y 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知x.x+y.y+8x+6y+25=0,求代数式(x.x-4y.y)/(x.x+4xy+4y.y)-x/(x+2y)的 已知x^2+y^2-4x-8y+20=0,则logx(y^x)的值是 已知x^2+4y^2-4x+4y+5=0,求(y^4-x^4)/(y-2x)(x+y)*2x-y 已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)} 已知实数x.y满足根号(x+y-8)+根号(8-x-y)=根号(3x-y-4)+根号(x-2y+7),求x,y 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 已知4x=9y求(1)x+y/y (2)y-x/2x 已知(z-x)∧2-4(x-y)(y-x)=0求x+z-2y+8的值