代换法是代数中重要的解题方法．对于不少校以难的数学问题，用常规解法，不是无从下手便是解题异常繁杂．这时，若能根据问题的特点，进行巧妙的代换，往往可化繁为简，化难为易，收到事半功倍的功效．现举例说明，供参考．例1计算：1995×19941994－1994×19951995分析若按常 Substitution method is an important problem solving method in algebra. For many mathematics problems that are difficult to solve, using routine solutions, it is not impossible for them to solve the problem. At this time, if you can according to the characteristics of the problem, ingenious substitution, you can often simplify the complex, difficult to change, and get twice the result with half the effort. Here is an example for reference. Example 1 Calculation: 1995×1994 1994-1994×1995 1995 Analysis If Routine