已知y=x^2-2x+1/x^2-1÷x^2-x/x+1*5x试说明在代数式有意义的条件下,不论x取何值,y的值都不变.是除以不是除,

已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 已知x,y满足约束条件：x-y+1>=0,x+y-2>=0,x mathematica软件,已知y[x],Y=f1(x),X(x)=f2(x),如何plot Y[X]?y[x_] := x + 9.81/2*x*xk=1X[x] = x - k*y'[x]/(1 + (y'[x])^2)^0.5Y[x] = y[x] + k/(1 + (y'[x])^2)^0.5Plot[{y[x],Y[X],},{x,0,2}] 已知x方-4x+4+|y+x|=0,求2x+x方/x方y-x方÷x方+4x+4/y方-2y+1×(X+2)的值 已知x(x-1)-(x^2-y)=-3.求x^2+y^2-2xy 已知x^2+y^2-8x+12y+52=0 ,求1/2x-1/x-y(x-y/2x-x^2+y^2) 已知x^2+y^2-8x+12y+52=0 ,求1/2x-1/x-y(x-y/2x-x^2+y^2) 已知实数x,y满足x-ay-1>=0,2x+y>=0,x 已知x(x+1)-(x²+y)=3求2/x²+y²-xy 1.(x-2y)(x+2y)-(x平方+y)(x平方-y) 2.(2x-y)(y+2x)-(2y+x)(2y-x)3.已知：x+y=6,x平方-y平方=48,求x,y的值4.x平方-2x分之x+2 -- x平方-4x+4分之x-1 已知x(x-1)-(x²-y)=-3,求(x²y+xy²)÷xy-2y 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 已知:【(x²+y²)-(x-y)²+2y(x-y)】/4y=1,求4x/4x²-y²-1/2x+y 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 已知2x/x²-y²÷M=1/y-x,求m 已知(2x)/(x²-y²)÷m=(1)/(x-y),求m 已知x,y为实数,且y=根号2x-6+根号(3-x)+1,求x根号2x÷根号x/y