若x^2+y^2-2x+4y-20=01,若x^2+y^2-2x+4y-20=0,则x^2+y^2的最小值____5-√5______2,从原点作圆x^2+y^2-2x=0的弦,则各条弦中点M的轨迹方程____x^2+y^2-x=0_______3,若实数x,y满足x^2+y^2-2x+4y=0,则x-2y的最大值___10_______4,若点

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 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 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x,y,z成等差数列,则(z-x)^2-4(x-y)(y-x)= 若x=-1/4,能否确定代数式(2x-y)(2x+y)+(2x-y)(y-4x)+2y(y-3x)的值? 若X=负四分之一,能否确定代数式(2X-Y)(2X+Y)+(2X-Y)(Y-4X)+2Y(Y-3X)的值? 若x-y=1 化简（x+y)(x^2+y^2)(x^4+y^4)(x^8+y^8)(x^16+y^16) 若x+y=4,则多项式1/2(x+y)+4(x-y)-3（x-y）-3/2(x+y)-x+y值是（） 4x方y/(x-2y)(x+2y)怎么算[x方/x-2y]-4x方y/(x-2y)(x+2y)=? 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 [(x+y)(x-y)-(x-y)²+2y(x-y)]÷4y (x+y)^2(x-y)^2(x^4+x^2y^2+y^4)=? 若f(x+y,y/x)=x^2-y^2,则F(X,Y)= y'=（y/x）^2+y/x+4微分方程