x/(x-2)-2/(x^2-4x+4)=1x/(x-2)-2/{(x-2)(x-2)}=1因为（x-2）不等于0所以约去x-2得x-2/(x-2)=1同分母得{x(x-2)-2}/(x-2)=1x(x-3)=0x=0或x=3x=0带入原式不成立,所以x=3
