已知x^2+y^2-4x+y+4.25=0 求y^-x+3xy值

已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知3x*+xy-2y*=0,求(x/y)-(y/x)-(x*+y*)/(xy)的值.*是平方 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>0 2x+y+3=xy 求5x+4y最小值 已知x^2+y^2-4x+y+4.25=0 求y^-x+3xy值 已知x^2+3xy-4y^2=0(y≠0),求x-y/x+y的值. 已知x-y=4xy,求x-2xy-y分之2x+3xy-2y的值! 已知y-x-2xy=0,求3x+xy-3y/y-xy-x的值 已知y-x-2xy=0,求(3x+xy-3y)\(y-xy-x)的值 已知x-3y=0,求（2x+y)/(x^2-2xy+y^2)*(x-y)的值 已知x-3y=0,求(2x+y)/(x^2-2xy+y^2)*(x-y)的值. 已知x-3y=0,求(2x+y)(x-y)/x^2-2xy+y^2的值