(创新扩展)已知{x-y+2>=0,x+y-4>=0,2x-y-5
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^2+4y^2-4x+4y+5=0,求(y^4-x^4)/(y-2x)(x+y)*2x-y
已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值
已知x²+4x+y²-2y+5=0,则x+y=
已知x²+4x+y-2y+5=0求x+2y
已知x²+y²-2x+4y+5=0,求x+y
已知x,y>0 2x+y+3=xy 求5x+4y最小值
已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)}
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
已知5x-4y=0且xy不等于0,求x^2+y^2/x^2-y^2-x+y/x-y的值
已知x²+y²-2x+4y+5=0,求X^4-y^4/2x^2+xy-y²·2x-y/xy