我们将等差数列求公差的五个公式视为“五朵金花”.它们结构简单,记忆方便,用来求解某些等差数列问题,可以简化解题过程,提高解题效率.公式1 d=(a_m-a_n)/(m-n)(m≠n).推导由等差数列的通项公式,得a_m=a_1+(m-1)d,a_n=a_1+(n-1)d.两式对应相减消去a_1,可得公式1. We treat the five formulas of tolerance as the “five golden flowers.” They are simple in structure and easy to memorize, and are used to solve some arithmetic sequence problems, which can simplify the process of solving problems and improve the efficiency of solving problems. Formula 1 d = (a_m-a_n) / (mn) (m ≠ n). Deriving the general formula of the arithmetic progression, we get a_m = a_1 + (m-1) d, a_n = a_1 + (n-1) d. Two corresponding subtraction elimination a_1, available formula 1.