x/(x-2) - 2/(x^2-4x+4) = 1
x/(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)=1
x(x-3)=0
x=0 或 x=3
x=0带入原式不成立,所以x=3