4x^3-4x^2y-xy^2+y^3=0
1个回答

4x^3-4x^2y-xy^2+y^3=0

4x^3-4x^2y+xy^2-2xy^2+y^3=0

x(4x^2-4xy+y^2)-2xy^2+y^3=0

x(2x-y)^2-y^2(2x-y)=0

(2x-y)(2x^2-xy-y^2)=0

(2x-y)(2x^2-2xy+xy-y^2)=0

(2x-y)[2x(x-y)+y(x-y)]=0

(2x-y)(2x+y)(x-y)=0

所以2x-y=0或2x+y=0或x-y=0

若2x-y=0

则y=2x

(x^2+y^2)/xy

=(x^2+4x^2)/(2x*x)

=5/2

若2x+y=0

则y=-2x

(x^2+y^2)/xy

=(x^2+4x^2)/(-2x*x)

=-5/2

若x-y=0

则y=x

(x^2+y^2)/xy

=(x^2+x^2)/(x*x)

=2