x^2+4y^2-4x+20y+8=0,求x+y=____.

x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 x*x+2x+y*y-4y+5=0 x= y= 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)的值 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? {x+y=1 ,xy=-6{x(2x-3)=0,y=x²-1{(3x+4y-3)(3x+4y+3)=0,3x+2y=5{(x-y+2)(x+y)=0,x²+y²=8{(x+y)((x+y-1)=0,(x-y)(x-y-1)=0 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 [(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x= 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? x^2+y^2-2x+4y-20=0则y/x的最大值,x+y的最大值 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 已知x^2+4y^2-4x+8y+8=0,求x+y 求x ,y 9x^2+4y^2-12x-8y+8=0 x+5y+2=0,则4^2x+y*8^y-x 已知|5x-y-8|+(7y-x+2)=0则4x+6y 已知x^2+4y^2-2x-2x+8y+5=0,求x^2-y^2/2x^2+xy-y^2*2y-y/xy-y/(x^2+y^2/y)^2的值 (x-4y)(2x+y)=