y=x(2-x),(0

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 求y=(x^2)+2x(x≥0) y=-x+2x(x 已知x>0,Y>0,如何证x^2/y+y^2/x>=x+y 变量x,y满足x-2y=0,x x*x+2x+y*y-4y+5=0 x= y= 设Z=X+Y,其中X,Y满足X+2Y>=0,X-Y Y=X^2X (X>0) 求导Y=X^2X (X>0) 求d(Y)/d(X) 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 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*x+4x+y*y-2y+5=0,则x*x+y*y=? 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值 设x大于1,y大于0,x^y+x^-y=2根号二,x^y-x^-y等于? (X,Y) f(x,y)={12y^2,0 先化简,再求值 [2/3x - 2/x+y（x+y/3x -x-y）]*x/x-y,其中5x+3y=0 先化简,再求值:[3x-2/x+y(x+y/3x-x-y)]/(x-y/x),其中5x+3y=0 y=1-x^2 x>=0 ,y=sin|x|/x x