题目先化简,再求值:(xx−2+1x−2)÷x2+2x+1x2−4(\frac{x}{x-2}+\frac{1}{x-2})÷\frac{x^2+2x+1}{x^2-4}(x−2x+x−21)÷x2−4x2+2x+1,其中x=3x=3x=3.知识点：分式的化简求值章节：数与式 / 分式
