题目中含有两个限制性条件是常见的排列组合问题,对此,很多同学解决起来往往会顾此失彼,使思维深陷泥沼.下面,给同学们介绍一种可以顺畅解决此类问题的方法.例1 7个人站成一行,甲不能站在最左端,乙不能站在最右端,则不同的站法有多少种?分析第一步,安排甲、乙,既然甲不站在最左端,就让甲从2号站位开始向右顺推,当甲站定后,再让乙从最靠左的站位开始向右顺 The problem contains two restrictive conditions is a common arrangement and combination of problems, many students will often find it difficult to solve the problem, so thinking is in a quandary. Now, to students a smooth solution to such problems. 1 7 individuals stand in line, A can not stand on the far left, B can not stand on the far right, then how many different station method? Analysis of the first step, arrange A, B, since A does not stand at the far left, let A from Station No. 2 start to the right push, when a station set, let B from the leftmost station to the right along