题目先化简(x2x+1−x)÷x2−1x2+2x+1(\frac{x^2}{x+1}-x)÷\frac{x^2-1}{x^2+2x+1}(x+1x2−x)÷x2+2x+1x2−1,再从111,−1-1−1,−2-2−2中选择合适的xxx值代入求值.知识点：分式的化简求值章节：数与式 / 分式
