已知x+y=30,x-y=20,则2（x-2y）-132的值为_____.

已知f(x+y,y/x)=x^2-y^2,则f(x,y)= 已知F(X+Y,X-Y)=X^2*Y+X*Y^2,则F(X,Y)=? 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x.y满足X2-y2=2xy.则x-y/x+y=?x. 已知2x=3y,则y分之x=< >,y分之x+y=< >. 已知x+y=30,x-y=20,则2（x-2y）-132的值为_____. 比例线段：已知x/y=2/3,则 x/x+y= ,x-y/x+y= 要过程! 已知|x+y-3|+(x-y)2=0则 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知方程组{(X+Y)-3(X-Y)=7,2(X+Y)+(X-Y）=-7}则(X+Y)(X-Y)= 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y 已知x/5=y/3,则(x/x+y)+(y/x-y)-(yxy/xxx-yxy) 已知,x分之一减y分之一=x-y分之一,则y/x+x/y 已知x≠y,x^2-x=y^2-y,求x+y的值. 已知x>0,Y>0,如何证x^2/y+y^2/x>=x+y