x^2+y^2-2x+4y+4=0则x-2y的最小值高二数学

已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? x*x+2x+y*y-4y+5=0 x= y= 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 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-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= (x-4y)(2x+y)= 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 设实数x,y 满足x²+4y²+2x-4y+2+0 则x+y= x^2+y^2-2x+4y-20=0则y/x的最大值,x+y的最大值 如果有理数x.y满足x^2+y^2+4x-6y+13=0,则y^x=? x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知3x-4y=0,则x^2-y^2/x^2+y^2 已知x^2+y^2-4x+2y+5=0则x^y=? 已知x^2+4x+y^2+2y+5=0,则x^y= .|x-2y-3|+|2x-y+4|=0则x=y= x^2+y^2+16x-4y+68=0,则x+y=? 已知X^2+Y^2+16X-4Y+68=0,则X+Y=----------- x+5y+2=0,则4^2x+y*8^y-x