(x^2-2x)^2=2x^2-4x+3
[x(x-2)]^2=2x(x-2)+3
设x-2=a
(xa)^2-2xa-3=0
(xa+1)(xa-3)=0
xa=-1或3
因为a=x-2
所以x(x-2)=-1,解得x=1
x(x-2)=3,解得x=3或-1
x=1或-1或3