近年中考题、竞赛题中常有分式求值问题,其特征是题型小,求值难度大.但是若能巧妙应用所学知识,注重技巧性的探讨,则易化繁就简,使问题迎刃而解.下面略举几例. 一、抓住分式求值问题中已知式的连等特征,巧妙利用式子中可取的特殊值,达到求值目的. In recent years, there are often questions of fractional evaluation in the mid-examination and competition questions, which are characterized by the small size of the questions and the difficulty of evaluation. However, if they can skillfully apply what they have learned and pay attention to the discussion of skills, they will be simplified and simplified. Conclude the solution. Here are a few examples. 1. Take advantage of the known features of the fractional evaluation problem and use the special values ​​in the formula to achieve the purpose of evaluation.