本文标题给出的公式是一个广为人知的简单事实 .若巧妙地应用它去解有关问题 ,往往能收到意想不到的效果 .下面以竞赛题为例谈应用它解题的技巧 ,供同学们参考 .例 1　已知三个质数之积恰好等于它们和的 5倍 ,则这三质数为 .解　设这三个质数为a、b、c ,由题意得 :abc =5(a+b + The formula given in the title of this article is a well-known simple fact. If it is applied skillfully to solve the relevant problems, it can often receive unexpected results. The following uses the contest title as an example to discuss the skills of applying it for students’ reference. Example 1 It is known that the product of three primes is exactly equal to 5 times their sum, then the three primes are. Solve the three primes as a, b, c, from the question meaning: abc = 5 (a + b +